Curable composition

ABSTRACT

The present invention has its object to provide a curable composition which comprises an amidine compound as a non-organotin catalyst and shows good elongation, flexibility, surface curability, depth curability and adhesiveness; the above object can be achieved by a non-organotin curable composition which comprises: (A) an organic polymer containing a silyl group capable of crosslinking under siloxane bond formation, the silyl group being a group represented by the general formula (1): —SiR 1 X 2 ; (B) an amidine compound (B-1) as a silanol condensation catalyst; and (C) a carboxylic acid, wherein the ratio between the number of moles (b) of all nitrogen atoms in the (B-1) component of the composition and the number of moles (c) of all carboxyl groups in the (C) component of the composition, namely the ratio (b)/(c), is higher than 2.

TECHNICAL FIELD

The present invention relates to a curable composition which comprisesan organic polymer containing a silicon atom-bound hydroxyl orhydrolyzable group and containing a silyl group capable of crosslinkingunder siloxane bond formation (hereinafter referred to as a “reactivesilyl group”).

BACKGROUND ART

It is known that organic polymers containing at least one reactive silylgroup in the molecule have properties such that they are crosslinkedunder siloxane bond formation resulting from hydrolysis and otherreactions of the reactive silyl group due to moisture and the like, evenat room temperature to give rubber-like cured products.

Among these reactive silyl group-containing polymers, those polymerswhich have a polyoxyalkylene type or polyisobutylene type main chainskeleton are disclosed in Patent Document 1, Patent Document 2 and thelike and have already been produced industrially and are in wide use insuch fields as sealants, adhesives and coatings.

Curable compositions to be used in preparing sealants, adhesives,coatings and like compositions as well as rubber-like cured productsobtained by curing thereof are required to have various characteristicssuch as curability, adhesiveness, mechanical characteristics and storagestability.

Since moisture in the air causes curing of curable compositionscomprising such a reactive silyl group-containing organic polymer asmentioned above, a great difference tends to arise between thecurability of the composition inside (depth curability) and the surfacecurability. In particular, in the case of one-pack type curablecompositions containing no moisture therein, a marked difference tendsto arise between depth curability and surface curability. Generallydesired are curable compositions showing rapid curability not only inthe surface layer but also in the depths.

For obtaining cured products from a curable composition comprising areactive silyl group-containing organic polymer, a silanol condensationcatalyst is used. Generally used as the silanol condensation catalystare organotin type catalysts having a carbon-tin bond such as dibutyltinbis(acetylacetonate), since they render the composition excellent inboth surface curability and depth curability simultaneously and causerapid increase in initial strength of cured products obtained. In recentyears, however, the toxicity of organotin type compounds have beenpointed out and development of non-organotin catalysts has been lookedfor.

Patent Document 3, Patent Document 4 and Patent Document 5 disclose, assilanol condensation catalysts, catalyst systems comprising acombination of an amine compound and a carboxylic acid. However, curablecompositions using the non-organotin type silanol condensation catalystsdescribed in the above-cited patent documents are sometimes insufficientin surface curability and, further, tend to decrease in adhesivenesswith the increasing addition level of carboxylic acid.

On the other hand, while the technology of preparing a non-organotintype silanol condensation catalyst by using an amine compound and thecarboxylic acid mentioned above in combination, there are only arelatively small number of examples disclosing a catalyst system inwhich an amine compound is used alone. Patent Document 6 discloses atechnology which uses an aryl group-substituted biguanide compound, suchas 1-(o-tolyl)biguanide, as a silanol condensation catalyst. As thedescription in the example section in Patent Document 6 discloses thatcure was effected over such a long period as one week, it is difficultto attain any practical level of curability with a catalyst system usingan amine compound alone.

On the other hand, investigations have also been carried out to improvethe curability of compositions by modifying the structure of reactivesilyl group-containing organic polymers. For example, Patent Document 7discloses a curable composition containing an organic polymerterminating in a reactive silyl group having three hydroxyl orhydrolyzable groups (such silyl group hereinafter referred to also as a“T terminal group”), for example a trialkoxysilyl group, and it isdisclosed that such a T terminal group-containing organic polymer, whenan organotin type catalyst is used as a silanol condensation catalyst,shows higher activity as compared with an organic polymer terminating ina reactive silyl group containing two hydroxyl or hydrolyzable groups(such silyl group hereinafter referred to also as a “D terminal group”,for example a dialkoxysilyl group.

As shown above, it is a task very high in degree of difficulty todevelop a curable composition satisfactory in all of such practicalcharacteristics as surface curability, depth curability and adhesivenessusing a non-organotin type silanol condensation catalyst while retainingthe elongation and flexibility of cured products obtained therefrom;under the existing circumstances, however, early development of suchcomposition is earnestly awaited.

Patent Document 1: Japanese Kokai Publication S52-73998

Patent Document 2: Japanese Kokai Publication S63-6041

Patent Document 3: Japanese Kokai Publication H05-117519

Patent Document 4: Japanese Kokai Publication 2001-342363

Patent Document 5: WO 04/31300

Patent Document 6: Japanese Kokai Publication 2005-248175

Patent Document 7: WO 98/47939

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a curablecomposition which comprises a reactive silyl group-containing organicpolymer and an amidine compound as a non-organotin catalyst and showsgood elongation, flexibility, surface curability, depth curability andadhesiveness.

The present inventors made intensive investigations to accomplish theabove object and, as a result, found that when use is made of a Dterminal group-containing organic polymer (A), an amidine compound (B-1)as a silanol condensation catalyst (B) and a carboxylic acid (C) forincreasing the catalytic activity and, further, when the ratio betweenthe number of moles (b) of all nitrogen atoms in the component (B-1)contained in the composition and the number of moles (c) of all carboxylgroups in the component (C) contained in the composition, namely theratio (b)/(c), is higher than 2, a curable composition having goodelongation, flexibility, surface curability, depth curability andadhesiveness can be obtained in spite of the catalyst being anon-organotin catalyst. Based on this finding, the present invention hasnow been completed.

That is, the present invention relates to a non-organotin curablecomposition, which comprises:

(A) an organic polymer containing a silyl group capable of crosslinkingunder siloxane bond formation, the silyl group being a group representedby the general formula (1):

—SiR¹X₂  (1)

(wherein R¹ represents a group selected from among alkyl groupscontaining 1 to 20 carbon atoms, aryl groups containing 6 to 20 carbonatoms, aralkyl groups containing 7 to 20 carbon atoms andtriorganosiloxy groups represented by (R′)₃SiO— in which R′ is ahydrocarbon group containing 1 to 20 carbon atoms, the three R′ groupsmay be the same or different, and X represents a hydroxyl group or ahydrolyzable group and the two X groups may be the same or different);(B) an amidine compound (B-1) as a silanol condensation catalyst; and(C) a carboxylic acid,

wherein the ratio between the number of moles (b) of all nitrogen atomsin the (B-1) component of the composition and the number of moles (c) ofall carboxyl groups in the (C) component of the composition, namely theratio (b)/(c), is higher than 2.

One preferred embodiment relates to the above-mentioned curablecomposition, wherein a main chain skeleton of the (A) component organicpolymer contains at least one atom selected from among a hydrogen atom,a carbon atom, a nitrogen atom, an oxygen atom and a sulfur atom.

One further preferred embodiment relates to the above-mentioned curablecomposition, wherein the (A) component organic polymer comprises atleast one species selected from the group consisting of polyoxyalkylenepolymers, saturated hydrocarbon polymers and (meth)acrylate esterpolymers.

One further preferred embodiment relates to the above-mentioned curablecomposition, wherein the polyoxyalkylene polymer is a polyoxypropylenepolymer.

One further preferred embodiment relates to the above-mentioned curablecomposition, which contains the (B-1) component in an amount of 0.001 to20 parts by weight per 100 parts by weight of the component (A).

Preferred as applications of the curable composition according to thepresent invention is a sealant or an adhesive which comprises thecurable composition as described above.

The present invention provides a curable composition which comprises areactive silyl group-containing organic polymer and in which an amidinecompound is used as a non-organotin catalyst and which is excellent inelongation, flexibility, surface curability, depth curability andadhesiveness.

DETAILED DESCRIPTION OF THE INVENTION

In the following, the present invention is described in detail.

The present invention includes a non-organotin type curable compositionwhich comprises a specific reactive silyl group-containing organicpolymer, a specific silanol condensation catalyst and a carboxylic acid.The “non-organotin type curable composition”, so referred to herein, isdefined as a composition in which the addition level of an organotincompound is not higher than 50% by weight in the compound componentseach acting as a silanol condensation catalyst.

In the composition, a D terminal group-containing organic polymer (A) isused as a reactive silyl group-containing organic polymer, an amidinecompound (B-1) as a silanol condensation catalyst (B) and a carboxylicacid (C) as a catalytic activity enhancer and the ratio between thenumber of moles (b) of all nitrogen atoms in the (B-1) componentcontained in the composition and the number of moles (c) of all carboxylgroups in the (C) component contained in the composition, namely theratio (b)/(c), is higher than 2.

The curable composition of the invention comprises, as an essentialconstituent (A), a reactive silyl group-containing organic polymer(hereinafter referred to also as “component (A)”, “reactive silylgroup-containing organic polymer (A)” or “organic polymer (A)”).

The organic polymer (A) has, on an average, at least one reactive silylgroup per molecule. The reactive silyl group, so referred to herein, isan organic group containing hydroxyl groups or hydrolyzable groups eachbound to a silicon atom. The reactive silyl group-containing organicpolymer (A) is crosslinked under siloxane bond formation as a result ofa reaction promoted by a silanol condensation catalyst.

As the reactive silyl group, there may be mentioned groups representedby the general formula (1):

—SiR¹X₂  (1)

(R¹ is at least one group selected from the group consisting of groupsselected from among alkyl groups containing 1 to 20 carbon atoms, arylgroups containing 6 to 20 carbon atoms, aralkyl groups containing 7 to20 carbon atoms and triorganosiloxy groups represented by (R′)₃SiO— inwhich each R′ is a hydrocarbon group containing 1 to 20 carbon atoms andthe three R′ groups may be the same or different, and two X groups areindependently a hydroxyl group or a hydrolyzable group).

The organic polymer, which terminates in a reactive silyl grouprepresented by the general formula (1) and contains two X groups (eachbeing a hydroxyl group or a hydrolyzable group) bound to the siliconatom, is superior in elongation, flexibility and storage stability to anorganic polymer which terminates in a reactive silyl group containingthree X groups (each being a hydroxyl group or a hydrolyzable group)bound to the silicon atom.

The curable composition of the present invention, which comprises areactive silyl group-containing organic polymer (A) as the maincomponent, is better in compatibility with the silanol condensationcatalyst, namely the amidine compound (B-1), as compared with acomposition which comprises, as the main component, such an inorganicpolymer as polydimethylsiloxane, hence is preferred.

The curable composition comprising an organic polymer (A) is excellentin curability and the cured products obtained therefrom arecharacterized by excellent adhesiveness.

Further, for the same reasons, the organic polymer (A) preferably has amain chain skeleton containing at least one atom selected from among ahydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom and asulfur atom.

The main chain skeleton of the organic polymer (A) is not particularlyrestricted but includes, polyoxyalkylene type polymers such aspolyoxyethylene, polyoxypropylene, polyoxybutylene,polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymers andpolyoxypropylene-polyoxybutylene copolymers; ethylene-propylene typecopolymers; polyisobutylene, copolymers of isobutylene and isoprene orthe like, polychloroprene, polyisoprene, copolymers of isoprene orbutadiene and acrylonitrile and/or styrene or the like; polybutadieneand copolymers of isoprene or butadiene and acrylonitrile and styrene orthe like; hydrocarbon type polymers such as hydrogenated polyolefinpolymers derived from these polyolefin type polymers by hydrogenation;polyester type polymers obtained by condensation of a dibasic acid suchas adipic acid and a glycol, or ring-opening polymerization of a lactone(s); (meth)acrylate ester polymers obtained by radical polymerization ofsuch a compound as ethyl (meth)acrylate and butyl (meth)acrylate; vinylpolymers obtained by radical polymerization of such a compound as a(meth)acrylate ester compound, vinyl acetate, acrylonitrile and styrene;graft polymers obtained by polymerizing a vinyl compound in suchpolymers as mentioned above; polysulfide type polymers; polyamide typepolymers such as polyamide 6 produced by ring-opening polymerization ofε-caprolactam, polyamide 6.6 produced by polycondensation ofhexamethylenediamine and adipic acid, polyamide 6.10 produced bypolycondensation of hexamethylenediamine and sebacic acid, polyamide 11produced by polycondensation of ε-aminoundecanoic acid, polyamide 12produced by ring-opening polymerization of ε-aminolaurolactam, andcopolymer polyamides composed of a plurality of the polyamides mentionedabove; polycarbonate type polymers such as polycarbonates produced bypolycondensation of bisphenol A and carbonyl chloride; diallyl phthalatetype polymers; and like organic polymers.

Preferred among those mentioned above are organic polymers (A) having,as the main chain skeleton, saturated hydrocarbon type polymers such aspolyisobutylene, hydrogenated polyisoprene and hydrogenatedpolybutadiene, polyoxyalkylene type polymers, (meth)acrylate esterpolymers and polysiloxane type polymers, in view of their relatively lowglass transition temperature and of good low-temperature resistance ofcured products obtained therefrom.

The glass transition temperature of the reactive silyl group-containingorganic polymer (A) is not particularly restricted but preferably is nothigher than 20° C., more preferably not higher than 0° C., mostpreferably not higher than −20° C. When the glass transition temperatureis higher than 20° C., the viscosity of the curable compositionincreases in the winter season or in cold districts, developing atendency toward lowered workability and, further, the flexibility ofcured products obtained decreases and the elongation thereof tends todecrease.

The glass transition temperature mentioned above can be determined byDSC measurement according to the method prescribed in JIS K 7121.

A curable composition comprising, as the main component, a saturatedhydrocarbon type polymer and an organic polymer whose main chainskeleton is a polyoxyalkylene type polymer and a (meth)acrylate esterpolymer is more preferred since, when it is used as an adhesive orsealant, low-molecular-weight components scarcely migrate to (i.e.stain) adherends.

Further, an organic polymer whose main chain skeleton is apolyoxyalkylene type polymer and a (meth)acrylate ester polymer isparticularly preferred since it is high in moisture permeability and,when used as a main component of a one-pack type adhesive or sealant, itis excellent in depth curability and gives cured products excellent inadhesiveness. Most preferred is an organic polymer whose main chainskeleton is a polyoxyalkylene type polymer.

The polyoxyalkylene type polymer to be used as the main chain skeletonof the organic polymer (A) is a polymer having a repeating unitrepresented by the general formula (2):

—R⁴—O—  (2)

(R⁴ is a straight or branched alkylene group containing 1 to 14 carbonatoms).

The group R⁴ in the general formula (2) is not particularly restrictedbut may be any of the straight or branched alkylene groups containing 1to 14 carbon atoms and, among those, straight or branched alkylenegroups containing 2 to 4 carbon atoms are preferred.

The repeating unit defined by the general formula (2) is notparticularly restricted but includes, for example, —CH₂O—, —CH₂CH₂O—,—CH₂CH(CH₃) O—, —CH₂CH(C₂H₅) O—, —CH₂C(CH₃)₂O— and —CH₂CH₂CH₂CH₂O—.

The polyoxyalkylene type polymer may have one repeating unit species ora plurality of repeating unit species. In the case of use in the fieldof sealants and the like, in particular, an organic polymer (A) in whichthe main component of the main chain skeleton is a propylene oxidepolymer is preferred since such polymer is noncrystalline and relativelylow in viscosity.

A method of producing such a polyoxyalkylene type polymer is notparticularly restricted but may be any of the methods known in the art.For example, mention may be made of the method using an alkali catalystsuch as KOH, the method disclosed in Japanese Kokai PublicationS61-215623 which uses, as a catalyst, a transition metal-porphyrincomplex, such as a complex obtained by reacting an organoaluminumcompound with porphyrin, the methods disclosed in Japanese KokokuPublications S46-27250 and S59-15336 and U.S. Pat. Nos. 3,278,457,3,278,458, 3,278,459, 3,427,256, 3,427,334 and 3,427,335, among others,which use, as a catalyst, a composite metal cyanide complex, the methoddisclosed in Japanese Kokai Publication H10-273512 which uses, as acatalyst, a polyphosphazene salt, and the method disclosed in JapaneseKokai Publication H11-060722 which uses, as a catalyst, a phosphazenecompound.

The method of producing a reactive silyl group-containingpolyoxyalkylene type polymer is not particularly restricted but may beany of the methods known in the art. For example, mention may be made ofthe methods disclosed in Japanese Kokoku Publications S45-36319 andS46-12154, Japanese Kokai Publications S50-156599, S54-6096, S55-13767,S55-13468 and S57-164123, Japanese Kokoku Publication H03-2450 and U.S.Pat. Nos. 3,632,557, 4,345,053, 4,366,307 and 4,960,844, among others,and the methods disclosed in Japanese Kokai Publications S61-197631,S61-215622, S61-215623, S61-218632, H03-72527, H03-47825 and H08-231707,among others, according to which polymers high in molecular weight(number average molecular weight of 6,000 or higher) and narrow inmolecular weight distribution (Mw/Mn of 1.6 or below) can be obtained.

In formulating the curable composition using the reactive silylgroup-containing polyoxyalkylene type polymer mentioned above, thepolymer may comprise a single species or a combination of a plurality ofspecies thereof.

The saturated hydrocarbon type polymer to be used as the main chainskeleton of the organic polymer (A) is a polymer whose molecules aresubstantially free of any carbon-carbon unsaturated bond, except for anaromatic ring, and is excellent in heat resistance, weather resistance,durability and a moisture barrier property.

The saturated hydrocarbon type polymer is not particularly restrictedbut there may be mentioned (i) polymers derived from an olefin compoundcontaining 2 to 6 carbon atoms, such as ethylene, propylene, 1-buteneand isobutylene as the repeating unit species, (ii) polymers derivedfrom a diene type compound, such as butadiene and isoprene as therepeating unit species, and (iii) polymers obtained by copolymerizingthe above-mentioned diene type compound and the above-mentioned olefintype compound, followed by hydrogenation. Among these, isobutylene typepolymers and hydrogenated polybutadiene type polymers are preferred inview of ease of functional-group introduction into an end thereof, easeof molecular weight control and adjustability of the number of terminalfunctional groups, among others; isobutylene type polymers are morepreferred.

The isobutylene type polymer may be such one that all of the repeatingunits are derived from isobutylene or a copolymer with another compound.When the isobutylene type copolymer is used as the main chain skeleton,the polymer preferably has an isobutylene-derived repeating unitcontent, in each molecule, of not lower than 50% by weight, morepreferably not lower than 80% by weight, particularly preferably 90 to99% by weight, so that the cured products obtained may have excellentrubber characteristics.

A method of producing the saturated hydrocarbon type polymer is notparticularly restricted but may be any of various conventionalpolymerization methods. Among them, the living polymerization method thedevelopment of which has been remarkable in recent years is preferredand, for example, the Inifer polymerization found by Kennedy et al. (J.P. Kennedy et al., J. Polymer Sci., Polymer Chem. Ed., 1997, 15, p.2843) may be mentioned as a method of producing isobutylene-basedpolymers using the living polymerization method. This polymerizationmethod enables introduction of various functional groups into molecularends and the isobutylene type polymers obtained are known to have amolecular weight of about 500 to 100,000 with a molecular weightdistribution of not broader than 1.5.

A method of producing the reactive silyl group-containing saturatedhydrocarbon polymer is not particularly restricted but may be any of themethods known in the art, for example the methods disclosed in JapaneseKokoku Publications H04-69659 and H07-108928, Japanese KokaiPublications S63-254149, S64-22904 and H01-197509 and Japanese PatentsNos. 2539445 and 2873395 and Japanese Kokai Publication H07-53882.

In formulating the curable composition using the above-mentionedreactive silyl group-containing saturated hydrocarbon type polymer, thepolymer may comprise a single species or a combination of a plurality ofspecies thereof.

A (meth)acrylate ester polymer to be used as the main chain skeleton ofthe organic polymer (A) is a polymer in which the repeating unit isderived from a (meth)acrylate ester compound. The expression“(meth)acrylate ester” refers to an acrylate ester and/or a methacrylateester and has the same meaning also in the description which follows.

The (meth)acrylate ester compound to be used as the repeating unit isnot particularly restricted but includes such (meth)acrylate compoundsas (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate,n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl(meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate,n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl(meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate,2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate,dodecyl (meth)acrylate, phenyl (meth)acrylate, toluoyl (meth)acrylate,benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate,γ-(methacryloyloxypropyl)trimethoxysilane,γ-(methacryloyloxypropyl)dimethoxymethylsilane, (meth)acrylicacid-ethylene oxide adducts, trifluoromethylmethyl (meth)acrylate,2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl(meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate,perfluoroethyl (meth)acrylate, trifluoromethyl (meth)acrylate,bis(trifluoromethylmethyl) (meth)acrylate,2-trifluoromethyl-2-perfluoroethylethyl (meth)acrylate,2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl(meth)acrylate and 2-perfluorohexadecylethyl (meth)acrylate.

The (meth)acrylate ester polymer includes copolymers of a (meth)acrylateester compound and a vinyl compound copolymerizable therewith. The vinylcompound is not particularly restricted but includes: styrene compoundssuch as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, andstyrenesulfonic acid and salts thereof; silyl group-containing vinylcompounds such as vinyltrimethoxysilane and vinyltriethoxysilane; maleicacid, maleic anhydride, and maleic acid monoalkyl esters and dialkylesters; fumaric acid and fumaric acid monoalkyl esters and dialkylesters; maleimide type compounds such as maleimide, methylmaleimide,ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide,octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide andcyclohexylmaleimide; nitrile group-containing vinyl compounds such asacrylonitrile and methacrylonitrile; amide group-containing vinylcompounds such as acrylamide and methacrylamide; vinyl esters such asvinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate andvinyl cinnamate; alkenes such as ethylene and propylene; conjugateddienes such as butadiene and isoprene; vinyl chloride, vinylidenechloride, allyl chloride and allyl alcohol. It is also possible to use aplurality of these as copolymerization components.

Among the (meth)acrylate ester polymers obtained from the compoundsmentioned above, those organic polymers which comprise, as the mainchain skeleton, a copolymer of a styrene compound and a (meth)acrylatecompound are preferred since they give cured products excellent inphysical properties; those organic polymers which comprise, as the mainchain skeleton, a copolymer of an acrylate ester compound and amethacrylate ester compound are more preferred, and those organicpolymers which comprise, as the main chain skeleton, a polymer of anacrylate ester compound are particularly preferred.

For use in general architectural fields, the curable composition isrequired to be low in viscosity, while the cured products obtainedtherefrom are required to be low in modulus and high in elongation,weather resistance and thermal stability.

More preferred as ones meeting these requirements are organic polymers(A) whose main chain skeleton is derived from a butyl acrylate compound.

On the other hand, for use in automotive or like fields, the curedproducts obtained are required to be excellent in oil resistance.

More preferred as one giving cured products excellent in oil resistanceis an organic polymer (A) whose main chain skeleton is a copolymermainly derived from ethyl acrylate.

Curable compositions comprising the organic polymer (A) whose main chainskeleton is an ethyl acrylate-based copolymer tend to give curedproducts somewhat inferior in low-temperature characteristics(low-temperature resistance) in spite of their being excellent in oilresistance. For improving the low-temperature characteristics,replacement is made of a part of ethyl acrylate with butyl acrylate.Since, however, an increased proportion of butyl acrylate tends toimpair the good oil resistance, the proportion thereof is preferably nothigher than 40%, more preferably not higher than 30%, in cases of afield where oil resistance is required.

The use, as a comonomer component, of 2-methoxyethyl acrylate or2-ethoxyethyl acrylate which has an oxygen atom introduced into the sidechain alkyl group is also preferred for improving low-temperaturecharacteristics and the like without causing decrease in oil resistance.

Since, however, the introduction of an alkoxy group having an ether bondin the side chain tends to render the cured products obtained inferiorin thermal stability, the proportion thereof is preferably not higherthan 40% in cases of use where thermal stability is required.

As mentioned above, it is possible to obtain an organic polymer (A)whose main chain skeleton is an ethyl acrylate-based copolymer and whichis suited for various uses or can meet requirements by selecting thecomonomer component species and varying the proportion thereof takinginto consideration such physical properties as oil resistance, thermalstability and low temperature characteristics as required of the curedproducts obtained. For example, there may be mentioned, without anylimitative meaning, copolymers of ethyl acrylate, butyl acrylate and2-methoxyethyl acrylate copolymer (weight ratio: 40-50/20-30/30-20) asexamples excellent in balance among such physical properties as oilresistance, thermal stability and low-temperature characteristics.

In the practice of the present invention, these preferred compounds maybe copolymerized and, further, block-copolymerized with another compoundand, on such occasion, the content of these preferred compounds ispreferably not lower than 40% by weight.

A method of producing the (meth)acrylate ester polymer is notparticularly restricted but may be any of the methods known in the art.Among them, the living radical polymerization method is preferably usedin particular in view of the ease of high-rate introduction of acrosslinking functional group into a molecular chain end and thepossibility of obtaining polymers narrow in molecular weightdistribution and low in viscosity.

The polymers obtained by ordinary free radical polymerization using, forexample, an azo compound or peroxide as a polymerization initiator tendto show an increased molecular weight distribution value generally notlower than 2 and an increased level of viscosity.

Among the methods of producing (meth)acrylate ester polymers using theabove-mentioned “living radical polymerization method”, the “atomtransfer radical polymerization method” which uses an organic halide orsulfonyl halide compound as an initiator and a transition metal complexas a catalyst is preferred as the method of producing (meth)acrylateester polymers containing a specific functional group since it has notonly such characteristics of the “living radical polymerization” as thenarrowness in molecular weight distribution and the capability to givepolymers low in viscosity but also a high degree of freedom in selectingthe initiator and catalyst and the capability to provide the polymerswith a halogen or the like at ends thereof relatively advantageous tofunctional-group exchange reactions.

As for the atom transfer radical polymerization method, there may bementioned, for example, the method described in Matyjaszewski et al.,Journal of the American Chemical Society (J. Am. Chem. Soc.), 1995, 117,p. 5614.

A method of producing the reactive silyl group-containing (meth)acrylateester polymer is not particularly restricted but includes, for example,the free radical polymerization method using a chain transfer agent, asdisclosed in Japanese Kokoku Publications H03-14068 and H04-55444 andJapanese Kokai Publication H06-211922, the atom transfer radicalpolymerization method disclosed in Japanese Kokai PublicationH09-272714, and the like.

It is also possible to use a (meth)acrylate ester copolymer derived froma plurality of the (meth)acrylate ester compounds mentioned above as themain chain skeleton of the organic polymer (A).

As typical examples of the (meth)acrylate ester copolymer derived from aplurality of (meth)acrylate ester compounds, there may be mentionedcopolymers whose main chain skeleton substantially comprises: arepeating unit having an alkyl group containing 1 to 8 carbon atoms asrepresented by the general formula (3):

—CH₂—C(R⁵)(COOR⁶)—  (3)

(R⁵ is a hydrogen atom or a methyl group and R⁶ is an alkyl groupcontaining 1 to 8 carbon atoms); and a repeating unit having an alkylgroup containing 9 or more carbon atoms as represented by the generalformula (4):

—CH₂—C(R⁵)(COOR⁷)—  (4)

(R⁵ is as defined above referring to the general formula (3) and R⁷ isan alkyl group containing 9 or more carbon atoms).

The group R⁶ in the general formula (3) is not particularly restrictedbut may be any of the alkyl groups containing 1 to 8 carbon atoms, forexample a methyl group, an ethyl group, a propyl group, an n-butylgroup, a t-butyl group and a 2-ethylhexyl group; among these, alkylgroups containing 1 to 4 carbon atoms are preferred.

The group R⁶ contained in the copolymers is not always restricted to asingle alkyl group species.

The group R⁷ in the general formula (4) is not particularly restrictedbut may be any of the alkyl groups containing 9 or more carbon atoms,for example a lauryl group, a dodecyl group, a cetyl group, a stearylgroup and a behenyl group. Among these, alkyl groups containing 10 to 30carbon atoms are preferred and long-chain alkyl groups containing 10 to20 carbon atoms are more preferred.

The group R⁷ contained in the copolymers is not always restricted to asingle alkyl group species.

The (meth)acrylate ester copolymer substantially comprises the repeatingunits defined by the general formula (3) and general formula (4). Theterm “substantially” as used herein means that the total content of therepeating units defined by the general formulas (3) and (4) in thecopolymer is not lower than 50% by weight, and the total content of therepeating units defined by the general formulas (3) and (4) in thecopolymer is preferably not lower than 70%.

The content ratio between the repeating units of general formulas (3)and (4) occurring in the copolymer as expressed in terms of the weightratio (general formula (3): general formula (4)) is preferably 95:5 to40:60, more preferably 90:10 to 60:40.

The (meth)acrylate ester copolymer comprises a copolymer of(meth)acrylate ester compounds used as the repeating units defined bythe general formulas (3) and (4) and a vinyl compound copolymerizabletherewith.

As the vinyl compound, there may be mentioned, for example, acrylicacids such as acrylic acid and methacrylic acid; amide group-containingcompounds such as acrylamide, methacrylamide, N-methylolacrylamide andN-methylolmethacrylamide, epoxy group-containing compounds such asglycidyl acrylate and glycidyl methacrylate, amino group-containingcompounds such as diethylaminoethyl acrylate, diethylaminoethylmethacrylate and aminoethyl vinyl ether; and, further, such compounds asacrylonitrile, styrene, α-methylstyrene, alkyl vinyl ethers, vinylchloride, vinyl acetate, vinyl propionate and ethylene.

These reactive silyl group-containing organic polymers may be usedsingly or in combination of two or more species. More specifically, itis also possible to use an organic-polymer blend comprising two or morespecies selected from the group consisting of reactive silylgroup-containing polyoxyalkylene type polymers, reactive silylgroup-containing saturated hydrocarbon type polymers and reactive silylgroup-containing (meth)acrylate ester polymers.

A method of producing the organic polymer blend comprising a reactivesilyl group-containing polyoxyalkylene type polymer and a reactive silylgroup-containing (meth) acryl ester polymer is not particularlyrestricted but there may be mentioned, for example, the methodsdisclosed in Japanese Kokai Publications S59-122541, S63-112642,H06-172631 and H11-116763, and the like.

The organic-polymer blend comprising a reactive silyl group-containingsaturated hydrocarbon type polymer and a reactive silyl group-containing(meth)acrylate ester polymer is not particularly restricted but mentionmay be made of the polymers disclosed in Japanese Kokai PublicationsH01-168764 and 2000-186176, and the like.

Further, in addition to those mentioned above, the organic-polymerblends comprising a reactive silyl functional group-containing(meth)acrylate ester polymer can also be produced by a method comprisingpolymerizing a (meth)acrylate ester monomer in the presence of areactive silyl group-containing polymer. This production method is notparticularly restricted but there may be mentioned, for example, themethods disclosed in Japanese Kokai Publications S59-78223, S59-168014,S60-228516 and S60-228517.

In the main chain skeleton of the organic polymer (A), there may furtherbe present, if necessary, another repeating unit containing, forexample, a urethane bond, so long as the effects of the presentinvention are not significantly lessened thereby.

The urethane bond-containing repeating unit is not particularlyrestricted but there may be mentioned, for example, a repeating unitcomprising a group formed by the reaction between an isocyanato groupand an active hydrogen group (the group thus formed is hereinafterreferred to also as an “amide segment”).

The amide segment is an organic group represented by the general formula(5):

—NR⁸—C(═O)—  (5)

(R⁸ is a hydrogen atom or an organic group).

The amide segment is not particularly restricted but includes, forexample, a urethane group formed by the reaction between an isocyanatogroup and a hydroxyl group; a urea group formed by the reaction betweenan isocyanato group and an amino group; and a thiourethane group formedby the reaction between an isocyanato group and a mercapto group.

Those organic groups formed by the reaction of an active hydrogen in theurethane group, the urea group and the thiourethane group with anisocyanato group also fall within the definition of “amide segment” asgiven herein.

A method of producing the reactive silyl group-containing organicpolymer containing an amide segment in the main chain skeleton thereofis not particularly restricted but there may be mentioned, for example,the method comprising reacting an active hydrogen-terminated organicgroup-containing organic polymer with an excess of a polyisocyanatecompound to give a polymer having an isocyanato group at a polyurethanetype main chain end and, thereafter or simultaneously therewith,reacting all or part of the isocyanato groups in the polymer with agroup W in a silicon compound represented by the general formula (6):

W—R⁹—SiR¹X₂  (6)

(R⁹ is a divalent organic group, more preferably a divalent hydrocarbongroup containing 1 to 20 carbon atoms; R¹ and the two X groups are asdefined hereinabove referring to the general formula (1); and W is agroup containing at least one active hydrogen selected from the groupconsisting of a hydroxyl group, a carboxyl group, a mercapto group andan amino (primary or secondary) group), as disclosed in Japanese KokokuPublication S46-12154 (U.S. Pat. No. 3,632,557), Japanese KokaiPublications S58-109529 (U.S. Pat. No. 4,374,237), S62-13430 (U.S. Pat.No. 4,645,816), H08-53528 (EP 0676403), and H10-204144 (EP 0831108),Japanese Kohyo Publication 2003-508561 (U.S. Pat. No. 6,197,912),Japanese Kokai Publications H06-211879 (U.S. Pat. No. 5,364,955),H10-53637 (U.S. Pat. No. 5,756,751), H11-100427, 2000-169544,2000-169545 and 2002-212415, Japanese Patent 3,313,360, U.S. Pat. Nos.4,067,844 and 3,711,445, Japanese Kokai Publication 2001-323040, and thelike.

Mention may also be made of a method comprising reacting an activehydrogen-containing group occurring at an end of an organic polymer withthe isocyanato group of a reactive silyl group-containing isocyanatecompound represented by the general formula (7):

O═C═N—R⁹—SiR¹X₂  (7)

(R⁹, the two R's and X are as defined above referring to the generalformula (6)), as disclosed in Japanese Kokai Publications H11-279249(U.S. Pat. No. 5,990,257), 2000-119365 (U.S. Pat. No. 6,046,270),S58-29818 (U.S. Pat. No. 4,345,053), H03-47825 (U.S. Pat. No.5,068,304), H11-60724, 2002-155145 and 2002-249538, WO 03/018658, WO03/059981, and the like.

The active hydrogen-terminated group-containing organic polymer is notparticularly restricted but includes, for example, hydroxylgroup-terminated oxyalkylene polymers (polyether polyols), polyacrylicpolyols, polyester polyols, hydroxyl group-terminated saturatedhydrocarbon type polymers (polyolefin polyols), polythiol compounds andpolyamine compounds.

Preferred among these are those organic polymers whose main chainskeleton comprises a polyether polyol, polyacrylic polyol and polyolefinpolyol components, since they have a relatively low glass transitiontemperature and give cured products excellent in low-temperatureresistance.

Those organic polymers comprising a polyether polyol component are lowin viscosity, have good workability and give cured products showing gooddepth curability and adhesiveness, hence are particularly preferred.Curable compositions in which an organic polymer containing apolyacrylic polyol and saturated hydrocarbon type polymer component aremore preferred since they give cured products having good weatherresistance and thermal stability.

The polyether polyol preferably has, on an average, at least 0.7terminal hydroxyl group per molecule.

The production method thereof is not particularly restricted but may beany of the methods known in the art, including, for example, apolymerization method using an alkali metal catalyst, and apolymerization method of an alkylene oxide using a polyhydroxy compoundcontaining at least two hydroxyl groups per molecule as an initiator inthe presence of a double metal cyanide complex or cesium.

Among the polymerization methods mentioned above, the polymerizationmethod using a double metal cyanide complex is preferred since it givespolymers low in degree of unsaturation, narrow in molecular weightdistribution (Mw/Mn) and low in viscosity, which give cured productsexcellent in acid resistance and weather resistance, among others.

The term “polyacrylic polyol” refers to a polyol whose skeleton is a(meth)acrylic acid alkyl ester (co)polymer and whose molecule contains ahydroxyl group.

As for the production method thereof, the living radical polymerizationmethod is preferred and the atom transfer radical polymerization methodis more preferred because of capability of their giving polymers narrowin molecular weight distribution and possibly low in viscosity. Alsopreferred is the polymerization method involving the so-called SGOprocess in which an acrylic acid alkyl ester type compound iscontinuously bulk-polymerized under high-temperature and high-pressureconditions, as disclosed in Japanese Kokai Publication 2001-207157. Assuch a polyacrylic polyol, there may be mentioned ARUFON UH-2000(product of Toagosei Co., Ltd.), and the like.

The polyisocyanate compound is not particularly restricted but includes,for example, an aromatic type polyisocyanate such as toluene (tolylene)diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate;and an aliphatic type polyisocyanate such as isophorone diisocyanate andhexamethylene diisocyanate.

When the amide segment content is high in the main chain skeleton of theorganic polymer serving as the (A) component in the practice of thepresent invention, the organic polymer shows a high viscosity andsometimes gives a composition poor in workability. Conversely, the amidesegment in the main chain skeleton of the (A) component tends to improvethe curability of the composition according to the present invention.

The silicon compound defined by the general formula (6) is notparticularly restricted but there may be mentioned, for example, aminogroup-containing silane compounds such asγ-aminopropyldimethoxymethylsilane,N-(β-aminoethyl)-γ-aminopropyldimethoxymethylsilane,γ-(N-phenyl)aminopropyldimethoxymethylsilane,N-ethylaminoisobutyldimethoxymethylsilane,N-cyclohexylaminomethyldiethoxymethylsilane,N-cyclohexylaminomethyldiethoxymethylsilane andN-phenylaminomethyldimethoxymethylsilane; hydroxyl group-containingsilane compounds such as γ-hydroxypropyldimethoxymethylsilane; andmercapto group-containing silane compounds such asγ-mercaptopropyldimethoxymethylsilane.

As the silicon compound represented by the general formula (6), theremay further be mentioned Michael addition products derived from variousα,β-unsaturated carbonyl compounds and a primary amino group-containingsilane compound or Michael addition products derived from various(meth)acryloyl group-containing silane compounds and a primary aminogroup-containing compound, as disclosed in Japanese Kokai PublicationsH06-211879 (U.S. Pat. No. 5,364,955), H10-53637 (U.S. Pat. No.5,756,751), H10-204144 (EP 0831108) 2000-169544 and 2000-169545.

The reactive silyl group-containing isocyanate compound defined by thegeneral formula (7) is not particularly restricted but includes, forexample, γ-methyldimethoxysilylpropyl isocyanate,γ-methyldiethoxysilylpropyl isocyanate and dimethoxymethylsilylmethylisocyanate.

As the reactive silyl group-containing isocyanate compound defined bythe general formula (7), there may further be mentioned the reactionproducts derived from a silicon compound of the general formula (6) andan excess of a polyisocyanate compound, as disclosed in Japanese KokaiPublication 2000-119365 (U.S. Pat. No. 6,046,270).

The hydrolyzable group represented by X in the general formula (1) isnot particularly restricted but includes those hydrolyzable groups whichare known in the art, for example, a hydrogen atom, halogen atoms, andan alkoxy group, an acyloxy group, a ketoxymate group, an amino group,an amide group, an acid amide group, an aminooxy group, a mercapto groupand an alkenyloxy group. Among these, a hydrogen atom, an alkoxy group,an acyloxy group, a ketoxymate group, an amino group, an amide group, anaminooxy group, a mercapto group and an alkenyloxy group are preferred,and an alkoxy group is more preferred from the viewpoints of mildhydrolyzability and easy handleability.

The group R¹ in the general formula (1) is not particularly restrictedbut includes, for example, an alkyl group such as a methyl group and anethyl group, a cycloalkyl group such as a cyclohexyl group, an arylgroup such as a phenyl group, an aralkyl group such as a benzyl group,and a triorganosiloxy group represented by —OSi(R′)₃ wherein R′ is amethyl group, a phenyl group or the like. Among these, a methyl group ispreferred.

The reactive silyl group defined by the general formula (1) is notparticularly restricted but includes, for example, adimethoxymethylsilyl group, a diethoxymethylsilyl group and adiisopropoxymethylsilyl group. Among these, a dimethoxymethylsilyl groupis preferred since it has high activity and affords good curability andgood storage stability.

Further, a diethoxymethylsilyl group is particularly preferred since thealcohol formed upon hydrolysis reaction of the reactive silyl group ishighly safe ethanol.

A method of introducing the reactive silyl group is not particularlyrestricted but includes such methods known in the art as the methods (a)to (c) shown below.

(a) A method comprising: reacting a polymer containing such a functionalgroup as a hydroxyl group in the molecule with an organic compoundcontaining an active group reactive with this functional group as wellas an unsaturated group to give an unsaturated group-containing polymer;or copolymerizing a polymer containing such a functional group as ahydroxyl group in the molecule with an unsaturated group-containingepoxy compound to give an unsaturated group-containing polymer, and thenreacting the reaction product obtained with a reactive silylgroup-containing hydrosilane for hydrosilylation.(b) A method comprising reacting the unsaturated group-containingorganic polymer obtained in the same manner as described above in (a)with a compound containing a mercapto group and a reactive silyl group.(c) A method comprising reacting an organic polymer containing such afunctional group as a hydroxyl group, an epoxy group or an isocyanatogroup in the molecule with a compound containing a functional groupreactive with this function group and a reactive silyl group.

Among these methods, the method (a) or the method (c) in such a modethat a hydroxyl group-terminated polymer is reacted with a compoundcontaining an isocyanato group and reactive silyl group is preferred inview of the fact that a high conversion rate can be attained in arelatively short period of time.

The method (a) is more preferred since curable compositions based on thereactive silyl group-containing organic polymer obtained by the method(a) tends to be lower in viscosity than curable compositions based onthe organic polymer obtained by the method (c) and, as a result, curablecompositions having good workability can be obtained and, further, theorganic polymer obtained by the method (b) has a strongermercaptosilane-due odor as compared with the organic polymer obtained bythe method (a).

The hydrosilane compound to be used in carrying out the method (a) isnot particularly restricted but includes, for example, halogenatedsilanes such as methyldichlorosilane; alkoxysilanes such asmethyldimethoxysilane, methyldiethoxysilane, and phenyldimethoxysilane;acyloxysilanes such as methyldiacetoxysilane and phenyldiacetoxysilane;and ketoxymatesilanes such as bis(dimethylketoxymate)methylsilane andbis(cyclohexylketoxymate)methylsilane. Among these, alkoxyhydrosilanesare preferred because of the mild hydrolyzability and easy handleabilityof curable compositions based on the organic polymer (A) obtained and,among the alkoxyhydrosilanes, methyldimethoxysilane is preferred sincecurable compositions based on the organic polymer (A) obtained aresuperior in curability and restorability.

The synthetic method (b) is not particularly restricted but may be, forexample, the method of introducing a mercapto group- and reactive silylgroup-containing compound into an unsaturated-bond site in the organicpolymer by a radical addition reaction in the presence of a radicalinitiator and/or a radical generation source. The mercapto group- andreactive silyl group-containing compound is not particularly restrictedbut includes, for example, γ-mercaptopropylmethyldimethoxysilane,γ-mercaptopropylmethyldiethoxysilane and(mercaptomethyl)methyldiethoxysilane.

The method of reacting a hydroxyl group-terminated polymer with anisocyanato group- and reactive silyl group-containing compound accordingto the synthetic method (c) is not particularly restricted but may be,for example, a method disclosed in Japanese Kokai Publication H03-47825.The isocyanato group- and reactive silyl group-containing compound isnot particularly restricted but includes, for example,γ-isocyanatopropylmethyldimethoxysilane,γ-isocyanatopropylmethyldiethoxysilane,isocyanatomethyldimethoxymethylsilane andisocyanatomethyldiethoxymethylsilane.

The reactive silyl group-containing organic polymer (A) to be used mayhave either a straight chain structure or a branched chain structure inthe molecule thereof, and the number average molecular weight thereof,as expressed in terms of the value on a polystyrene equivalent basis asderived from the value measured by GPC, is preferably 500 to 100,000,more preferably 1,000 to 50,000, particularly preferably 3,000 to30,000. When the number average molecular weight is lower than 500, thecured products obtained tend to be inferior in elongationcharacteristics and, when it is in excess of 100,000, the resultingcurable composition becomes high in viscosity and tends to be inferiorin workability.

The number of reactive silyl groups contained in each molecule of theorganic polymer (A) is preferably not smaller than 1 on an average; itis preferably 1.1 to 5. When the number of reactive silyl groupscontained in each molecule is smaller than 1 on an average, the curablecomposition tends to be inferior in curability and the cured productsobtained show a tendency toward failure to exhibit a good rubber elasticbehavior.

The reactive silyl group may occur at a main chain end or at a sidechain end, or at both. In particular, when the reactive silyl groupoccurs only at a main chain end, the effective network size in theorganic polymer component contained in the cured products obtainedbecomes increased, so that it becomes easy to obtain rubber-like curedproducts showing high strength, high elongation and low elastic modulus.

The curable composition according to the present invention comprises, asessential components, an amidine compound (hereinafter sometimesreferred to as “component (B)” or “amidine compound (B-1)”) as a silanolcondensation catalyst (component (B)) and a carboxylic acid (hereinaftersometimes referred to as “component (C)” or “carboxylic acid (C)”) as apromoter (component (C)).

By using an amidine compound (B-1) as a silanol condensation catalyst,in spite of its being a non-organotin catalyst, it becomes possible forthe curable composition according to the present invention to show ahigh level of curability that cannot have been arrived at with theconventional amine compound-based silanol condensation catalysts knownin the art (aliphatic amines, aromatic amines, etc.) and for the curedproducts obtained to show good adhesiveness against various adherends.

As the conventional amine compound-based silanol condensation catalysts,there may be mentioned, for example, aliphatic primary amines such asmethylamine, propylamine, isopropylamine, butylamine, amylamine,2-ethylhexylamine, laurylamine, stearylamine and cyclohexylamine;aliphatic secondary amines such as dimethylamine, dipropylamine,diisopropylamine, dibutylamine, diamylamine, dioctylamine,bis(2-ethylhexyl)amine, dilaurylamine, dicetylamine, distearylamine andmethylstearylamine; aliphatic tertiary amines such as triamylamine,trihexylamine and trioctylamine; aliphatic unsaturated amines such astriallylamine and oleylamine; aromatic amines such as laurylaniline,stearylaniline and triphenylamine; and other amines such asmonoethanolamine, diethanolamine, triethanolamine, 3-hydroxypropylamine,diethylenetriamine, triethylenetetramine, benzylamine,3-methoxypropylamine, 3-lauryloxypropylamine,3-dimethylaminopropylamine, 3-diethylaminopropylamine, xylylenediamine,ethylenediamine, hexamethylenediamine, triethylenediamine,2,4,6-tris(dimethylaminomethyl)phenol, morpholine andN-methylmorpholine.

The carboxylic acid (C) to be used in combination with the amidinecompound (B-1) plays a role in enhancing the catalytic activity of theamidine compound (B-1).

As regards the mixing ratio between the amidine compound (B-1) andcarboxylic acid (C) in the silanol condensation catalyst, the relationbetween the number of moles of nitrogen atoms derived from the amidinecompound (B-1) and the number of moles of carboxyl groups derived fromthe carboxylic acid (C) is important, and it is important that the moleratio between them (number (b) of moles of all (B-1)-derived nitrogenatoms/number (c) of moles of all (C)-derived carboxyl groups) be higherthan 2 so that curable compositions showing good surface curability,depth curability and adhesiveness may be obtained.

The amidine compound (B-1) is not particularly restricted but may be anyof the amidine compounds known in the art. Among them, those amidinecompounds represented by the general formula (8) are preferred sincethey are high in catalytic activity and provide the organic polymer (A)with good curability.

R¹⁰N═CR¹¹—NR₂ ¹²  (8)

(R¹⁰, R¹¹ and the two R¹²s are independently a hydrogen atom or anorganic group. Any two or more of R¹⁰, R¹¹ and the two R¹²s may becombined together to form a ring structure.)

Preferred as R¹⁰ in the general formula (8) is a hydrogen atom or ahydrocarbon group since, in such a case, the amidine compound is readilyavailable and can provide the organic polymer (A) with good curability;more preferred is a hydrocarbon group in which the carbon atom atposition 1 is saturated.

When R¹⁰ is an organic group or a hydrocarbon group, the number ofcarbon atoms therein is preferably 1 to 20, more preferably 1 to 10,since, in such a case, the organic polymer (A) can be provided with goodcurability.

Preferred as R¹¹ in the general formula (8) are a hydrogen atom, a —NR₂¹³ group (in which the two R¹³s are independently a hydrogen atom or ahydrocarbon group containing 1 to 20 carbon atoms), a —NR¹⁴—C(═NR¹⁵)—NR₂¹⁶ group (in which R¹⁴, R¹⁵ and the two R¹⁶s are independently ahydrogen atom or a hydrocarbon group containing 1 to 20 carbon atoms), a—N═C(NR₂ ¹⁷)—NR₂ ¹⁸ group (in which the two R¹⁷ s and the two R¹⁸ s areindependently a hydrogen atom or a hydrocarbon group containing 1 to 20carbon atoms) or a hydrocarbon group containing 1 to 20 carbon atomssince, in such a case, the organic polymer (A) can be provided with goodcurability and the cured products obtained show good adhesiveness; morepreferred are a hydrogen atom, a —NR₂ ¹³ group (R¹³ being as definedabove), a —NR¹⁴—C(═NR¹⁵)—NR₂ ¹⁶ group (R¹⁴, R¹⁵ and the two R¹⁶s beingas defined above), a —N═C(NR₂ ¹⁷)—NR₂ ¹⁸ group (the two R¹⁷ s and thetwo R¹⁸s being as defined above) or a hydrocarbon group containing 1 to10 carbon atoms; particularly preferred are a —NR₂ ¹³ group (R¹³ beingas defined above), a —NR¹⁴—C(═NR¹⁵)—NR₂ ¹⁶ group (R¹⁴, R¹⁵ and the twoR¹⁶s being as defined above) or a —N═C(NR₂ ¹⁷)—NR₂ ¹⁸ group (the twoR¹⁷s and the two R¹⁸s being as defined above).

Those amidine compounds of the general formula (8) in which R¹¹ is an—NR₂ ¹³ group or a like organic group are called guanidine compounds.

Those amidine compounds of the general formula (8) in which R¹¹ is suchan organic group as the —NR¹⁴—C(═NR¹⁵)—NR₂ ⁵⁶ group and —N═C(NR₂ ¹⁷)—NR₂¹⁸ group mentioned above are called biguanide compounds.

Each of the two R¹²s in the general formula (8) is preferably a hydrogenatom or a hydrocarbon group containing 1 to 20 carbon atoms, morepreferably a hydrogen atom or a hydrocarbon group containing 1 to 10carbon atoms, since, in such a case, the amidine compound is readilyavailable and can provide the organic polymer (A) with good curability.

Since, when R¹¹ in the general formula (8) is an —NR¹⁴—C(═NR¹⁵)—NR₂ ¹⁶group (R¹⁴, R¹⁵ and the two R¹⁶s being as defined above), the curedproducts obtained show good adhesiveness, it is preferred that at leastone of R¹⁰, the two R¹²s, R¹⁴, R¹⁵ and the two R¹⁶s be an aryl group.

When R¹¹ in the general formula (8) is an —NR₂ ¹³ group (R¹³ being asdefined above), the curability of the curable composition tends todecrease with the increase in the number of aryl groups bound to thenitrogen atoms contained in the molecule and, therefore, it is preferredthat at least four of R¹⁰, the two R¹²s and the two R¹⁵s be either anorganic group other than an aryl group or a hydrogen atom.

In view of their ready availability and their ability to provide theorganic polymer (A) with good curability, those amidine compoundsrepresented by the general formula (8) in which any two or more of R¹⁰,R¹¹ and the two R¹²s are bound together to form a ring structure arepreferred, and those cyclic amidine compounds represented by the generalformula (9) are more preferred.

(R¹⁹, R²⁰ and R²¹ are independently a hydrogen atom or an organic group.R²⁰ and R²¹ may be bound together to form a ring structure.)

From the viewpoints of ready availability and ability to provide theorganic polymer (A) with excellent curability, R¹⁹ in the generalformula (9) is preferably a divalent hydrocarbon group containing 1 to10 carbon atoms, more preferably a divalent hydrocarbon group containing1 to 10 carbon atoms in which the carbon atom at position 1 issaturated, still more preferably a divalent hydrocarbon group containing1 to 5 carbon atoms in which the carbon atom at position 1 is saturated,particularly preferably a divalent hydrocarbon group containing 2 or 3carbon atoms in which the carbon atom at position 1 is saturated. Fromthe viewpoints of curability and adhesiveness, R²⁰ is preferably ahydrogen atom, an —NR₂ ¹³ group (R¹³ being as defined above) or ahydrocarbon group containing 1 to 20 carbon atoms, more preferably ahydrogen atom, an —NR₂ ¹³ group (R¹³ being as defined above) or ahydrocarbon group containing 1 to 10 carbon atoms, particularlypreferably an —NR₂ ¹³ group (R¹³ being as defined above). From theviewpoints of ready availability and ability to provide the organicpolymer (A) with excellent curability, R²¹ is preferably a hydrogen atomor a hydrocarbon group containing 1 to 20 carbon atoms, more preferablya hydrogen atom or a hydrocarbon group containing 1 to 10 carbon atoms.

From the viewpoint of ready availability and of ability to provide theorganic polymer (A) with good curability, it is preferred that R²⁰ andR²¹ be bound together to form a ring structure.

The amidine compound (B-1) preferably has a melting point of not lowerthan 23° C., more preferably not lower than 50° C., still morepreferably not lower than 80° C., particularly preferably not lower than120° C. When the melting point is lower than 23° C., an amidine compound(B-1)-derived liquid tends to bleed out, namely flow out onto thesurface of the cured product, causing a problem of soiling one's handupon touching of the hand with the cured product surface. The number ofcarbon atoms contained in the amidine compound (B-1) represented by thegeneral formula (8) is preferably not smaller than 2, more preferablynot smaller than 6, particularly preferably not smaller than 7.

When the number of carbon atoms is smaller than 2 (namely when themolecular weight is low), the volatility of the compound becomesincreased, causing a tendency toward pollution of the work environment.It is not necessary to particularly specify the upper limit to thenumber of carbon atoms contained in the amidine compound (B-1); it isgenerally preferred, however, that the number be not larger than 10,000.

For the same reasons as mentioned above, the amidine compound (B-1)preferably has a molecular weight of not lower than 60, more preferablynot lower than 120, particularly preferably not lower than 130. It isnot necessary to particularly specify the upper limit to the molecularweight; it is generally preferred, however, that the molecular weight benot higher than 100,000.

The amidine compound (B-1) (inclusive of the guanidine compound andbiguanide compound) is not particularly restricted but includesimidazole compounds such as imidazole, 2-methylimidazole and2-ethyl-4-methylimidazole; amidine compounds such as2-methyl-2-imidazoline, 2-ethyl-2-imidazoline, 2-n-propyl-2-imidazoline,2-isopropyl-2-imidazoline, 2-n-octyl-2-imidazoline,4,4-dimethyl-2-imidazoline, 4,5-dimethyl-2-imidazoline,1-(1-aminoethyl)-2-octyl-2-imidazoline, 2-n-undecyl-2-imidazoline,2-cyclohexyl-2-imidazoline, 2-benzyl-2-imidazoline,2-phenyl-2-imidazoline, 2-[(3,4-dichlorophenoxy)methyl]-2-imidazoline,1,4,5,6-tetrahydropyrimidine, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine,1-n-propyl-2-methyl-1,4,5,6-tetrahydropyrimidine,1,8-diazabicyclo[5.4.0]undec-7-ene (DBU),6-(dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene (DBA-DBU) and1,5-diazabicyclo[4.3.0]non-5-ene (DBN); guanidine compounds such asguanidine, 1,1,2-trimethylguanidine, 1,2,3-trimethylguanidine,1,1,3,3-tetramethylguanidine, 1,1,2,3,3-pentamethylguanidine,1-benzylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine,1,3-diphenylguanidine, 1,3-dibenzylguanidine,1-benzyl-2,3-dimethylguanidine, N-(2-imidazolin-2-yl)-1-naphthalenamine,2-phenyl-1,3-dicyclohexylguanidine, 1-benzylaminoguanidine,1-(benzyloxy)guanidine, 1,1′-[4-(dodecyloxy)-m-phenylene]bisguanidine,guanylthiourea,2-[(5,6,7,8-tetrahydronaphthalen-1-yl)amino]-2-imidazoline,1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD),7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD),7-isopropyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene,7-cyclohexyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene,7-phenyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene and2,3,5,6-tetrahydro-3-phenyl-1H-imidazo[1,2-a]imidazole; and biguanidecompounds such as biguanide, 1-methylbiguanide, 1-n-butylbiguanide,1-(2-ethylhexyl)biguanide, 1-n-octadecylbiguanide,1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide,1-allylbiguanide, 1-phenylbiguanide, 1-(o-tolyl)biguanide (OTBG),1-(2-chlorophenyl)biguanide, 1-benzylbiguanide, 2-benzylbiguanide,3-benzylbiguanide, N,N-diamidinoaniline, 1,5-ethylenebiguanide,1-morpholinobiguanide, 1-(4-chlorobenzyloxy)biguanide,1-n-butyl-N²-ethylbiguanide, 1,1′-ethylenebisbiguanide,1-[3-(diethylamino)propyl]biguanide,1-[3-(dibutylamino)propyl]biguanide,N′,N″-dihexyl-3,12-diimino-2,4,11,13-tetraazatetradecanedia midine,1-(morpholinosulfonyl)benzylbiguanide, 1-(hydroxymethyl)biguanide,1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidine and5-[3-(2,4,5-trichlorophenoxy)propoxy]-1-isopropylbiguanide. Either asingle species among these amidine compounds may be incorporated in thecurable composition or a combination of a plurality thereof may beincorporated in the curable composition.

Among the amidine compounds mentioned above, biguanide compounds arepreferred since the curable compositions obtained show goodadhesiveness. More specifically, biguanide, 1-n-butylbiguanide,1,1-dimethylbiguanide, 1-phenylbiguanide and OTBG are preferred, andOTBG is particularly preferred.

Such cyclic amidine compounds as 2-methyl-2-imidazoline,1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, DBU and DBN and such cyclicguanidine compounds as TBD, MTBD and7-cyclohexyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred, and TBDand MTBD are more preferred, in view of their ability to provide theorganic polymer (A) with good curability.

From the viewpoint that bleeding out from the cured products obtainedcan be inhibited, such amidine compounds having a melting point of notlower than 23° C. as TBD, 1-phenylguanidine, 1-n-butylbiguanide,1,1-dimethylbiguanide, 1-phenylbiguanide and OTBG are preferred, and1-phenylguanidine and OTBG are more preferred.

The carboxylic acid (C) to be used in combination with the amidinecompound (B-1) plays a role in enhancing the catalytic activity of theamidine compound (B-1) and produces the effect of improving the surfacecurability and depth curability of the curable composition and, at thesame time, produces the effect of improving the adhesiveness of thecured products obtained.

The carboxylic acid (C) is not particularly restricted but includesstraight-chain saturated fatty acids such as acetic acid, propionicacid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylicacid, 2-ethylhexanoic acid, pelargonic acid, capric acid, undecanoicacid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid,palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid,arachic acid, behenic acid, lignoceric acid, cerotic acid, montanicacid, melissic acid and lacceric acid; monoenoic unsaturated fatty acidssuch as undecylenic acid, linderic acid, tsuzuic acid, physeteric acid,myristoleic acid, 2-hexadecenoic acid, 6-hexadecenoic acid,7-hexadecenoic acid, palmitoleic acid, petroselinic acid, oleic acid,elaidic acid, asclepic acid, vaccenic acid, gadoleic acid, gondoic acid,cetoleic acid, erucic acid, brassidic acid, selacholeic acid, ximenicacid, lumequeic acid, acrylic acid, methacrylic acid, angelic acid,crotonic acid, isocrotonic acid and 10-undecenoic acid; polyenoicunsaturated fatty acids such as linoelaidic acid, linolic acid,10,12-octadecadienoic acid, hiragonic acid, α-eleostearic acid,β-eleostearic acid, punicic acid, linolenic acid, 8,11,14-eicosatrienoicacid, 7,10,13-docosatrienoic acid, 4,8,11,14-hexadecatetraenoic acid,moroctic acid, stearidonic acid, arachidonic acid,8,12,16,19-docosatetraenoic acid, 4,8,12,15,18-eicosapentaenoic acid,clupanodonic acid, nisinic acid and docosahexaenoic acid; branched fattyacids such as 1-methylbutyric acid, isobutyric acid, 2-ethylbutyricacid, isovaleric acid, tuberculostearic acid, pivalic acid,2,2-dimethylbutyric acid, 2-ethyl-2-methylbutyric acid,2,2-diethylbutyric acid, 2,2-dimethylvaleric acid,2-ethyl-2-methylvaleric acid, 2,2-diethylvaleric acid,2,2-dimethylhexanoic acid, 2,2-diethylhexanoic acid,2,2-dimethyloctanoic acid, 2-ethyl-2,5-dimethylhexanoic acid,neodecanoic acid and versatic acid; triple bond-containing fatty acidssuch as propiolic acid, tariric acid, stearolic acid, crepenynic acid,xymenynic acid and 7-hexadecynoic acid; alicyclic carboxylic acids suchas naphthenic acid, malvalic acid, sterculic acid, hydnocarpic acid,chaulmoogric acid, gorlic acid, 1-methylcyclopentanecarboxylic acid,1-methylcyclohexanecarboxylic acid,2-methylbicyclo[2.2.1]-5-heptene-2-carboxylic acid,1-adamantanecarboxylic acid, bicycle[2.2.1]heptanes-1-carboxylic acidand bicycle[2.2.2]octane-1-carboxylic acid; oxygen-containing fattyacids such as acetoacetic acid, ethoxyacetic acid, glyoxylic acid,glycolic acid, gluconic acid, sabinic acid, 2-hydroxytetradecanoic acid,ipurolic acid, 2,2-dimethyl-3-hydroxypropionic acid,2-hydroxyhexadecanoic acid, jalapinolic acid, juniperic acid,ambrettolic acid, aleuritic acid, 2-hydroxyoctadecanoic acid,12-hydroxyoctadecanoic acid, 18-hydroxyoctadecanoic acid,9,10-dihydroxyoctadecanoic acid, ricinolic acid, camlolenic acid,licanic acid, pheronic acid, cerebronic acid and2-methyl-7-oxabicyclo[2.2.1]-5-heptene-2-carboxylic acid; andhalogen-substituted monocarboxylic acids such as chloroacetic acid,2-chloroacrylic acid and chlorobenzoic acid.

As far as aliphatic dicarboxylic acids are concerned, there is noparticular restriction and there may be mentioned, for example saturateddicarboxylic acids such as adipic acid, azelaic acid, pimelic acid,suberic acid, sebacic acid, ethylmalonic acid, glutaric acid, oxalicacid, malonic acid, succinic acid, oxydiacetic acid, dimethylmalonicacid, ethylmethylmalonic acid, diethylmalonic acid, 2,2-dimethylsuccinicacid, 2,2-diethylsuccinic acid, 2,2-dimethylglutaric acid and1,2,2-trimethyl-1,3-cyclopentanedicarboxylic acid; and unsaturateddicarboxylic acids such as maleic acid, fumaric acid,acetylenedicarboxylic acid and itaconic acid.

As far as aliphatic polycarboxylic acids are concerned, there is noparticular restriction and there may be mentioned, for example,tricarboxylic acids such as aconitic acid, 4,4-dimethylaconitic acid,citric acid, isocitric acid and 3-methylisocitric acid. As aromaticcarboxylic acids, there may be mentioned aromatic monocarboxylic acidssuch as benzoic acid, 9-anthracenecarboxylic acid, atrolactic acid,anisic acid, isopropylbenzoic acid, salicylic acid and toluic acid; andaromatic polycarboxylic acids such as phthalic acid, isophthalic acid,terephthalic acid, carboxyphenylacetic acid and pyromellitic acid.

Either a single species among the carboxylic acid (C) used incombination with the amidine compound (B-1) may be incorporated into thecurable composition or a combination of a plurality thereof may beincorporated into the curable composition.

Among those mentioned above, monocarboxylic acids are more preferred,and chain monocarboxylic acids are still more preferred, in view oftheir good compatibility with the component (A).

The carboxylic acid (C) preferably has a melting point of not higherthan 65° C., more preferably −50 to 50° C., particularly preferably −40to 35° C. When the melting point of the carboxylic acid is in excess of65° C., the handling of the acid becomes difficult and the workabilitytends to become worsened.

The carboxylic acid (C) preferably has 5 to 20 carbon atoms, morepreferably 6 to 18 carbon atoms, particularly preferably 8 to 12 carbonatoms. When the number of carbon atoms is in excess of 20, the acidreadily becomes a solid and shows a tendency toward decreasedcompatibility with the component (A) and, therefore, the activity of thecurable composition tends to lower. On the other hand, when the numberof carbon atoms is not larger than 5, the carboxylic acid increases involatility and tends to emit an odor at raised levels.

From the viewpoints of availability and workability, as mentioned above,2-ethylhexanoic acid, octylic acid, oleic acid, naphthenic acid,2,2-dimethyloctanoic acid, 2-ethyl-2,5-dimethylhexanoic acid,neodecanoic acid and versatic acid are preferred among others.

The addition level of the (B-1) component is not particularly restrictedprovided that the requirement that the ratio (b)/(c) value mentionedabove is higher than 2 is satisfied. Preferably, the addition level is0.01 to 20 parts by weight, more preferably 0.5 to 15 parts by weight,particularly preferably 1 to 10 parts by weight, per 100 parts by weightof the (A) component organic polymer.

When the addition level of the (B-1) component is below 0.01 part byweight, any practical rate of curing may not be obtained in someinstances and, further, sometimes, it becomes difficult for the curingreaction to proceed to a sufficient extent. On the other hand, when theaddition level of the (B-1) component is in excess of 20 parts byweight, the pot-life becomes too short, so that the workability tends tobecome poor.

The addition level of the (C) component is not particularly restrictedprovided that the requirement that the ratio (b)/(c) value mentionedabove is higher than 2 is satisfied. Preferably, the addition level isabout 0.01 to 20 parts by weight, more preferably about 0.1 to 10 partsby weight, particularly preferably about 1 to 7 parts by weight, per 100parts by weight of the (A) component organic polymer. When the additionlevel of the (C) component is below 0.01 part by weight, any sufficientadhesiveness may not be obtained in some instances. On the other hand,when the addition level of the (C) component is in excess of 20 parts byweight, any practical level of depth curability may not be obtained insome instance.

While the curable composition of the present invention uses an amidinecompound as a silanol condensation catalyst, another silanolcondensation catalyst may be used, if necessary, in combination with theamidine compound so long as the effects of the present invention willnot be reduced.

The silanol condensation catalyst other than the amidine compound is notparticularly restricted but includes, for example, carboxylic acid metalsalts such as tin carboxylates, lead carboxylates, bismuth carboxylates,potassium carboxylates, calcium carboxylates, barium carboxylates,titanium carboxylates, zirconium carboxylates, hafnium carboxylates,vanadium carboxylates, manganese carboxylates, iron carboxylates, cobaltcarboxylates, nickel carboxylates and cerium carboxylates; titaniumcompounds such as tetrabutyl titanate, tetrapropyl titanate, titaniumtetrakis(acetylacetonate), bis(acetylacetonato)diisopropoxytitanium anddiisopropoxytitanium bis(ethyl acetoacetate); organotin compounds suchas dibutyltin dilaurate, dibutyltin maleate, dibutyltin phthalate,dibutyltin dioctanoate, dibutyltin bis(2-ethylhexanoate), dibutyltinbis(methyl maleate), dibutyltin bis(ethyl maleate), dibutyltin bis(butylmaleate), dibutyltin bis(octyl maleate), dibutyltin bis(tridecylmaleate), dibutyltin bis(benzyl maleate), dibutyltin diacetate,dioctyltin bis(ethyl maleate), dioctyltin bis(octyl maleate), dibutyltindimethoxide, dibutyltin bis(nonylphenoxide), dibutenyltin oxide,dibutyltin oxide, dibutyltin bis(acetylacetonate), dibutyltin bis(ethylacetoacetonate), reaction products of dibutyltin oxide-silicate compoundand reaction products of dibutyltin oxide-phthalic acid ester; aluminumcompounds such as aluminum tris(acetylacetonate), aluminum tris(ethylacetoacetate) and diisopropoxyaluminum ethyl acetoacetate; zirconiumcompounds such as zirconium tetrakis(acetylacetonate); various metalalkoxides such as tetrabutoxyhafnium; organic acid phosphoric acidesters; organic sulfonic acids such as trifluoromethanesulfonic acid anddodecylbenzenesulfonic acid; inorganic acids such as hydrochloric acid,phosphoric acid and boronic acid; and so forth.

The use of such a silanol condensation catalyst other than an amidinecompound in combination with the amidine compound is expected to enhancethe catalytic activity and thus improve the depth curability and surfacecurability of the curable composition and the adhesiveness and otherproperties of the cured products obtained. Among those enumerated above,titanium compounds, aluminum compounds and organic sulfonic acids, amongothers, are preferred since the surface curability of the organicpolymer (A) is more enhanced by the use thereof; diisopropoxytitaniumbis(ethyl acetoacetate), diisopropoxyaluminum ethyl acetoacetate anddodecylbenzenesulfonic acid are more preferred.

The combined use of titanium compounds is also preferred since the usegives curable compositions with increased strength and elongation; amongthem, diisopropoxytitanium bis(ethyl acetoacetate) is more preferred.The combined use of sulfonic acids is preferred since the solubility ofthe amidine compound (B-1) into the curable composition is increasedthereby; among them, dodecylbenzenesulfonic acid is more preferred inview of its ready availability.

Since, however, when an organotin compound is used in combination, thetoxicity of the curable composition tends to increase with the increasein organotin addition level, the addition level of the organotincompound is preferably as low as possible and, more specifically, it ispreferably not higher than 1 part by weight, more preferably not higherthan 0.5 part by weight, particularly preferably not higher than 0.05part by weight, per 100 parts by weight of the organic polymer (A);substantial absence thereof is most preferred.

The organotin compound addition level in the “non-organotin type curablecomposition” so referred to herein is such that the organotin compoundamounts to not more than 50% by weight, preferably not more than 30% byweight, more preferably not more than 10% by weight, particularlypreferably not more than 1% by weight, of the compound components actingas silanol condensation catalysts; substantial absence thereof is mostpreferred. The curable composition of the present invention ispreferably a non-organotin type curable composition and, from theviewpoints of toxicity and environmental stress, it is more preferably atin-free curable composition containing substantially none of such tincompounds as organotin type compounds and tin carboxylates, still morepreferably an organotin-free and carboxylic acid metal salt-free curablecomposition containing substantially none of organotin compounds andvarious carboxylic acid metal salts, particularly preferably a metalcatalyst-free curable composition containing substantially none of theabove-mentioned metal element-containing curing catalysts such ascarboxylic acid metal salts, titanium compounds, organotin compounds,organoaluminum compounds and zirconium compounds.

In cases where a metal compound other than an organotin is used incombination, the addition level thereof more specifically is preferablynot higher than 5 parts by weight, more preferably not higher than 2parts by weight, per 100 parts by weight of the organic polymer (A), andsubstantial absence thereof is most preferred.

In the curable composition of the present invention, there may beincorporated a plasticizer if necessary. The plasticizer functions as anagent for adjusting the viscosity and slump characteristics of thecurable composition and adjusting the tensile strength, elongation andlike mechanical characteristics of the cured products obtained.

The plasticizer is not particularly restricted but includes: phthalicacid esters such as dibutyl phthalate, diheptyl phthalate,bis(2-ethylhexyl) phthalate and butyl benzyl phthalate; nonaromaticdibasic acid esters such as dioctyl adipate, dioctyl sebacate, dibutylsebacate and isodecyl succinate; aliphatic esters such as butyl oleateand methyl acetylricinoleate; phosphoric acid esters such as tricresylphosphate and tributyl phosphate; trimellitic acid esters; chlorinatedparaffins; hydrocarbon type oils such as alkyldiphenyls and partiallyhydrogenated terphenyl; process oils; and epoxy type plasticizers suchas epoxidized soybean oil and benzyl epoxystearate.

Addition of a polymeric plasticizer containing a polymer component inthe molecule is preferred since such addition makes it possible tomaintain the initial characteristics of the cured products obtained fora long period of time and, further, improve the drying characteristics(also referred to as applicability) of an alkyd paint when it is appliedto the cured products obtained. The polymeric plasticizer is notparticularly restricted but includes: vinyl polymers obtained bypolymerization of vinyl monomers by various methods; polyalkylene glycolesters such as diethylene glycol dibenzoate, triethylene glycoldibenzoate and pentaerythritol esters; polyester type plasticizersderived from a dibasic acid such as sebacic acid, adipic acid, azelaicacid and phthalic acid and a dihydric alcohol such as ethylene glycol,diethylene glycol, triethylene glycol, propylene glycol and dipropyleneglycol; polyether polyols such as polyethylene glycol, polypropyleneglycol and polytetramethylene glycol, each having a molecular weight ofnot lower than 500, preferably not lower than 1000, or polyetherderivatives derived from such polyether polyols by esterification oretherification of one or both hydroxyl groups therein; polystyrenes suchas polystyrene and poly-α-methylstyrene; polybutadiene, polybutene,polyisobutylene, butadiene-acrylonitrile copolymers, polychloroprene andthe like.

Among these polymeric plasticizers, those highly compatible with theorganic polymer (A) are preferred and, for example, polyethers and vinylpolymers may be mentioned. Polyethers are more preferred since theyprovide the curable composition with good surface curability and depthcurability and cause no curing retardation after storage; morespecifically, polypropylene glycol is particularly preferred.

Further, vinyl polymers are preferred since they have high compatibilitywith the organic polymer (A) and provide the resulting cured productswith good weather resistance and thermal stability; among them, acrylicpolymers and/or methacrylic polymers are more preferred, and suchacrylic polymers as polyacrylic acid alkyl esters are particularlypreferred.

While the method of producing the polyacrylic acid alkyl esters is notparticularly restricted, the living radical polymerization method ispreferred because of capability of their giving polymers narrow inmolecular weight distribution and possibly low in viscosity, and theatom transfer radical polymerization method is more preferred. Alsoparticularly preferred is the method called “SGO process” and disclosedin Japanese Kokai Publication 2001-207157, which comprises continuouslybulk-polymerizing an acrylic acid alkyl ester type compound under hightemperature and high pressure conditions.

The number average molecular weight of the polymeric plasticizer isgenerally 500 to 15000, preferably 800 to 10000, more preferably 1000 to8000, particularly preferably 1000 to 5000, most preferably 1000 to3000. When the molecular weight of the polymeric plasticizer is too low,the plasticizer may escape from the cured products obtained with thelapse of time due to heat or rainfall and, as a result, it becomes nolonger possible to maintain the initial physical characteristics,staining by adhesion of dust may possibly be caused and the alkydapplicability tends to become poor. On the other hand, when themolecular weight is excessively high, the viscosity of the curablecomposition will increase and the workability tends to become poor.

The molecular weight distribution of the polymeric plasticizer is notparticularly restricted but preferably is narrow, for example narrowerthan 1.80, preferably not wider than 1.70, more preferably not widerthan 1.60, still more preferably not wider than 1.50, particularlypreferably not wider than 1.40, most preferably not wider than 1.30.

In the case of polyether type polymers, the number average molecularweight is determined by the end-group analysis and, in the case of otherpolymers, it is determined by the GPC method. The molecular weightdistribution (Mw/Mn) is measured by the GPC method (on the polystyreneequivalent basis).

The polymeric plasticizer may be a reactive silyl group-containing oneor a silyl group-free one and, in cases where a reactive silylgroup-containing polymeric plasticizer is added, the polymericplasticizer is preferably involved in the curing reaction and thus, theplasticizer can be prevented from migrating from the cured productsobtained.

The reactive silyl group-containing polymeric plasticizer is preferablya compound whose silyl group content is, on an average, not more thanone, preferably not more than 0.8, per molecule. When a reactive silylgroup-containing plasticizer, in particular a reactive silylgroup-containing oxyalkylene polymer, is added, it is preferred that thenumber average molecular weight thereof be lower than that of theorganic polymer (A) so that a satisfactory plasticizing effect may beobtained.

The plasticizer to be added may comprise a single species or acombination of a plurality of species. It is also possible to add alow-molecular-weight plasticizer and a polymeric plasticizer incombination. The plasticizer addition may also be made on the occasionof the production of the organic polymer (A).

When a plasticizer is added, the addition level thereof is preferably 5to 150 parts by weight, more preferably 10 to 120 parts by weight,particularly preferably 20 to 100 parts by weight, per 100 parts byweight of the organic polymer (A). At addition levels lower than 5 partsby weight, there is a tendency for the plasticizing effect to be littleproduced and, at levels exceeding 150 parts by weight, there arises atendency for the mechanical strength of the cured products to becomeinsufficient.

In the curable composition of the present invention, there may beincorporated an adhesiveness-imparting agent, if necessary.

The adhesiveness-imparting agent is a compound containing a hydrolyzablesilyl group and other functional group(s) in the molecule and, whenincorporated into the curable composition, effectively improves theadhesiveness of the resulting cured products to various adherends and/oreffectively removes (dehydrates) the moisture contained in the curablecomposition.

Further, the adhesiveness-imparting agent is a compound capable of notonly producing the effects mentioned above but also functioning as aphysical property modifier and/or a dispersibility-improving agent forinorganic fillers.

The hydrolyzable silyl group occurring in the adhesiveness-impartingagent may be any of those enumerated hereinabove as examples of thehydrolyzable group. Among those, a methoxy group, an ethoxy group, andthe like are preferred because of their proper rate of hydrolysis. Thenumber of hydrolyzable groups contained in each molecule of theadhesiveness-imparting agent is preferably not smaller than 2,particularly preferably not smaller than 3.

As examples of the functional group other than the hydrolyzable silylgroup as occurring in the adhesiveness-imparting agent, there may bementioned a substituted or unsubstituted amino group, mercapto group,epoxy group, carboxyl group, vinyl group, isocyanato group andisocyanurate group, and halogen atoms. In particular, substituted orunsubstituted amino group-containing adhesiveness-imparting agents arepreferred since they show good compatibility with the guanidine compound(B-1) and the like. Substituted or unsubstituted amino group-containingadhesiveness-imparting agents are preferred also in view of theirability to enhance the adhesiveness between the cured products obtainedand adherends.

The adhesiveness-imparting agent is not particularly restricted butincludes aminosilanes such as γ-aminopropyltrimethoxysilane,γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane,γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane,γ-(2-aminoethyl)aminopropyltrimethoxysilane,γ-(2-aminoethyl)aminopropylmethyldimethoxysilane,γ-(2-aminoethyl)aminopropyltriethoxysilane,7-(2-aminoethyl)aminopropylmethyldiethoxysilane,7-(2-aminoethyl)aminopropyltriisopropoxysilane,γ-(2-(2-aminoethyl)aminoethyl)aminopropyltrimethoxysilane,γ-(6-aminohexyl)aminopropyltrimethoxysilane,3-(N-ethylamino)-2-methylpropyltrimethoxysilane,2-aminoethylaminomethyltrimethoxysilane,N-cyclohexylaminomethyltriethoxysilane,N-cyclohexylaminomethyldiethoxymethylsilane,γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane,N-phenyl-γ-aminopropyltrimethoxysilane,N-phenylaminomethyltrimethoxysilane,N-benzyl-γ-aminopropyltrimethoxysilane,N-vinylbenzyl-γ-aminopropyltriethoxysilane,N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole,N-cyclohexylaminomethyltriethoxysilane,N-cyclohexylaminomethyldiethoxymethylsilane,N-phenylaminomethyltrimethoxysilane,(2-aminoethyl)aminomethyltrimethoxysilane andN,N′-bis[3-(trimethoxysilyl)propyl]ethylenediamine; ketimine typesilanes such asN-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, andcondensation products resulting from partial condensation of the silanesmentioned above.

Among the adhesiveness-imparting agents mentioned above,γ-aminopropyltrimethoxysilane is particularly preferred from theviewpoints of compatibility, transparency and availability.

The adhesiveness-imparting agent to be incorporated in the curablecomposition may comprise a single species or a combination of aplurality of species. In selecting the adhesiveness-imparting agent, itis preferred that one containing a hydrolyzable group of the samestructure as the hydrolyzable group occurring in the organic polymer (A)so that the surface curability of the curable composition may beprevented from changing during storage. Thus, when the hydrolyzablesilyl group in the organic polymer (A) is a methoxysilyl group, anadhesiveness-imparting agent with a methoxysilyl group structure shouldbe selected and, when the hydrolyzable silyl group in the organicpolymer (A) is an ethoxysilyl group, an adhesiveness-imparting agentwith an ethoxysilyl group structure should be selected.

To the curable composition of the present invention, there may be addeda filler, if necessary. The filler is not particularly restricted butincludes: reinforcing fillers such as fumed silica, precipitated silica,crystalline silica, fused silica, dolomite, silicic anhydride, hydroussilicic acid and carbon black; heavy calcium carbonate, colloidalcalcium carbonate, magnesium carbonate, diatomaceous earth, calcinedclay, clay, talc, titaniumoxide, bentonite, organicbentonite, ferricoxide, fine aluminum powder, flint powder, zinc oxide, activated zincwhite, shirasu balloons, glass microballoons, organic microballoonsbased on a phenol resin or a vinylidene chloride resin, organic powderssuch as PVC powder and PMMA powder; and fibrous fillers such asasbestos, glass fibers and filaments.

When a filler is added, the addition level thereof is preferably 1 to250 parts by weight, more preferably 10 to 200 parts by weight, per 100parts by weight of the organic polymer (A).

On the occasion of using the curable composition as a one-pack typeadhesive or sealant, it is preferred, for obtaining good storagestability, that such a filler as mentioned above be uniformly mixed witha dehydrating agent such as calcium oxide and the mixture be allowed tostand in a sealed bag made of an airtight material for a proper periodof time for dehydrating and drying, and then used, as disclosed inJapanese Kokai Publication 2001-181532 and the like.

When the cured products obtained are to be used in the fields ofapplication where transparency is required, a polymer powder containinga polymer of methyl methacrylate and the like, and noncrystallinesilica, are preferred as the filler to be added, as disclosed inJapanese Kokai Publication H11-302527 and the like; hydrophobic silicaand the like, as disclosed in Japanese Kokai Publication 2000-38560 andthe like, is more preferred.

The hydrophobic silica, so referred to herein, is a product derived bytreating the surface of the silicon dioxide fine powder generallyoccupied by silanol (—SiOH) groups with an organosilicon halide or analcohol for conversion of those groups to (—SiO-hydrophobic) groups. Thehydrophobic silica is not particularly restricted but includes, forexample, products obtained by treating silanol groups occurring on asilicon dioxide fine powder with dimethylsiloxane, hexamethyldisilazane,dimethyldichlorosilane, trimethoxyoctylsilane, trimethylsilane, and thelike. The untreated silicon dioxide fine powder whose surface isoccupied by silanol (—SiOH) groups is called hydrophilic silica finepowder.

When the cured products obtained are to be used in the fields ofapplication where high strength is required, silicon compounds such asfumed silica, precipitated silica, crystalline silica, fused silica,dolomite, silicic anhydride and hydrous silicic acid; carbon black,surface-treated finely divided calcium carbonate, calcined clay, clay,activated zinc white and the like are preferred as the filler to beadded, and the addition level thereof is preferably 1 to 200 parts byweight per 100 parts by weight of the organic polymer (A).

Further, when the cured products obtained are to be used in the fieldsof application where low strength and high elongation modulus arerequired, titanium oxide, calcium carbonate such as heavy calciumcarbonate, magnesium carbonate, talc, ferric oxide, zinc oxide andshirasu balloons are preferred as the filler to be added, and theaddition level thereof is preferably 5 to 200 parts by weight per 100parts by weight of the organic polymer (A).

When calcium carbonate is added, the tendency toward improvements in thebreaking strength, breaking elongation and adhesiveness of the curedproducts obtained increases as the specific surface area increases. Onlyone of these filler species may be added or a plurality of speciesthereof may be added in combination.

The example of addition of a plurality of additives is not particularlyrestricted but the combined use of a surface-treated fine calciumcarbonate and a calcium carbonate larger in particle diameter such asheavy calcium carbonate is preferred since cured products excellent inphysical characteristics can be obtained.

Preferred as the surface-treated fine calcium carbonate are those whoseparticle diameter is not larger than 0.5 μm and whose particle surfacehas been treated with a fatty acid and a fatty acid salt.

Preferred as the calcium carbonate having a large particle diameter arethose whose particle diameter is not smaller than 1 μm and whoseparticle surface has not been treated.

In cases where the curable composition is required to have goodworkability (releasability, etc.) or where the surface of the curedproducts obtained is required to be matted, organic balloons orinorganic balloons are preferred as the filler to be added. Thesefillers may be surface-treated or non-surface-treated, and only onespecies thereof may be added or a plurality of species thereof may beadded in admixture. For improving the workability (releasability, etc.),the particle diameter of the balloons is preferably not larger than 0.1mm and, for rendering the cured product surface matted, it is preferably5 to 300 μm.

The curable composition of the present invention, which gives curedproducts excellent in chemical resistance, is suited for use, inparticular, as a sealant, adhesive or like composition for siding boardsin ceramic and like systems and for housing outside-wall joints andoutside-wall tiles.

On the occasion of use in such fields of application, the cured productsobtained appear or exist on the joints or like observable surfaces and,therefore, it is desirable that the cured product design be in harmonywith the outside wall design. In recent years, in particular, thesputtering coating and the addition of colored aggregates, among others,have been employed for providing luxurious outside walls, so that thedesigns of cured products are becoming more and more important.

For obtaining luxurious designs, a scaly or granular substance isincorporated in the curable composition of the present invention. Theaddition of a granular substance gives sandy or sandstone-like roughsurfaces, and the addition of a scaly substance gives surfaces rendereduneven due to scales.

The cured products obtained are in harmony with luxurious outside wallsand are excellent in chemical resistance, so that the luxuriousappearance thereof can be maintained for a long period of time.

The scaly or granular substance is not particularly restricted butincludes, for example, one disclosed in Japanese Kokai PublicationH09-53063, and the diameter thereof is properly selected according tothe outside wall material and design and is preferably not smaller than0.1 mm, more preferably 0.1 to 5.0 mm. In the case of a scaly substance,the thickness of scales is preferably 1/10 to ⅕ (0.01 to 1.00 mm) of thediameter.

The addition level of the scaly or granular substance is properlyselected according to the size of the scaly or granular substance, theoutside-wall material and design and other factors; preferably, theaddition level is 1 to 200 parts by weight per 100 parts by weight ofthe curable composition.

The material of the scaly or granular substance is not particularlyrestricted but includes natural products such as silica sand and mica,synthetic rubbers, synthetic resins, and inorganic materials such asalumina. These may be appropriately colored according to the outsidewall material, design, and so forth so that the design quality of thecomposition applied to joints and so forth may be enhanced.

Preferred methods of finishing are those disclosed in Japanese KokaiPublication H09-53063 and the like.

The scaly or granular substance may be incorporated in advance in thecurable composition or may be admixed with the curable composition ofthe occasion of use thereof.

It is also possible, for the same purposes, to add balloons (preferablyhaving an average particle diameter of not smaller than 0.1 mm) to thecurable composition, thereby providing the resulting cured productsurface with a coarse feel such as a sandy or sandstone feel and,further, contributing to weight reduction. The “balloons” are sphericalhollow fillers.

The balloons are not particularly restricted but include, for example,those disclosed in Japanese Kokai Publications H10-251618, H02-129262,H04-8788, H04-173867, H05-1225, H07-113073, H09-53063, 2000-154368 and2001-164237 and WO 97/05201.

As the material of balloons, there may be mentioned inorganic materialssuch as glass, shirasu and silica; and organic materials such as phenolresins, urea resins, polystyrene and Saran. Mention may further be madeof composite materials of an inorganic material and an organic material;and laminates comprising a plurality of layers. These may be used singlyor a plurality species thereof may be used in combination.

It is also possible to use balloons subjected to surface coatingtreatment, treatment with various surface treatment agents or some othertreatment; as typical examples, there may be mentioned organic balloonscoated with calcium carbonate, talc, titanium oxide or the like, andinorganic balloons surface-treated with an adhesiveness-imparting agent.

Further, the balloons preferably have a particle diameter of not smallerthan 0.1 mm, more preferably 0.2 mm to 5.0 mm, particularly preferably0.5 mm to 5.0 mm. When the diameter is smaller than 0.1 mm, the additioneven in large amounts only increases the viscosity of the composition,sometimes failing to provide the resulting cured products with a coarsefeel.

When balloons are added, the addition level thereof can be properlyselected according to the intended decorative effect; it is preferredthat balloons having a particle diameter of not smaller than 0.1 mm beadded in an amount such that the volume concentration thereof in thecurable composition amounts to 5 to 25% by volume, more preferably 8 to22% by volume. When the volume concentration of balloons is below 5% byvolume, the desired coarse feel tends to become lost. At level exceeding25% by volume, the viscosity of the curable composition increases andthe workability thereof tends to become poor; further, the modulus ofthe cured products increases and the fundamental performancecharacteristics of the sealant or adhesive tend to become impaired.

On the occasion of adding balloons, it is also possible to add, incombination, such an anti-slip agent as the one disclosed in JapaneseKokai Publication 2000-154368 or such an amine compound capable ofrendering the resulting cured product surface uneven and matted as theone disclosed in Japanese Kokai Publication 2001-164237. Preferred asthe amine compound mentioned above are primary and/or secondary amineshaving a melting point of 35° C. or higher.

Also usable as the balloons are thermally expandable minute hollowparticles disclosed in Japanese Kokai Publication 2004-51701 or2004-66749, for instance. The “thermally expandable minute hollowparticles” are spherical plastic bodies made of a polymer shell material(vinylidene chloride type copolymer, acrylonitrile type copolymer orvinylidene chloride-acrylonitrile copolymer) with a low-boiling compoundsuch as a hydrocarbon containing 1 to 5 carbon atoms as sphericallyenclosed therein.

By adding thermally expandable minute hollow particles to the curablecomposition of the present invention, it becomes possible to obtain,without using any organic solvent at all, a thermally removable adhesivecomposition which, when no more required, can be peeled off with easeonly by heating without destruction of the adherend materials. This isbased on the mechanism such that when the adhesive portion is heated,the gas pressure inside the shells of the thermally expandable minutehollow particles increases and the polymer shell material is softenedand dramatically expanded to cause peeling at the adhesive interface.

When the curable composition of the present invention contains sealantcuring particles as well, the cured products obtained can have an unevenrough surface and, thus, the decorative feature thereof can be improved.The preferred diameter, addition level, material and the like of thesealant curing particles are disclosed in Japanese Kokai Publication2001-115142, and the diameter is preferably 0.1 mm to 1 mm, morepreferably 0.2 to 0.5 mm. The addition level is preferably 5 to 100parts by weight, more preferably 20 to 50 parts by weight, per 100 partsby weight of the curable composition. The material is not particularlyrestricted but may be any of the materials used in sealing compositions;thus, mention may be made of urethane resins, silicones, modifiedsilicones and polysulfide rubbers, for example.

Among those mentioned above, modified silicone type sealant curingparticles are preferred.

To the curable composition of the present invention, there may be addeda silicate, if necessary. The silicate acts as a crosslinking agent onthe organic polymer (A) and functions to bring about improvements in therestorability, durability and creep resistance of the cured productsobtained.

Further, the addition of a silicate brings about improvements in theadhesiveness and water-resistant adhesiveness and in the bond durabilityunder high-temperature and high-pressure conditions. The silicate is notparticularly restricted but includes, for example, tetraalkoxysilanes orpartial hydrolysis condensation products derived therefrom; morespecifically, there may be mentioned tetraalkoxysilanes (tetraalkylsilicates) such as tetramethoxysilane, tetraethoxysilane,ethoxytrimethoxysilane, dimethoxydiethoxysilane, methoxytriethoxysilane,tetra-n-propoxysilane, tetra-1-propoxysilane, tetra-n-butoxysilane,tetra-1-butoxysilane and tetra-t-butoxysilane as well as partialhydrolysis condensation products derived therefrom.

When a silicate is added, the addition level thereof is preferably 0.1to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per100 parts by weight of the organic polymer (A).

The tetraalkoxysilane-derived partial hydrolysis condensation productmentioned above is not particularly restricted but includes, forexample, products derived from tetraalkoxysilanes by addition of waterthereto to cause partial hydrolysis and condensation.

The addition of a tetraalkoxysilane-derived partial hydrolysiscondensation product is preferred since such condensation productproduces significant improvements in restorability, durability and creepresistance of the cured products obtained as compared with thecorresponding composition containing the tetraalkoxysilane addedthereto.

Commercially available as the tetraalkoxysilane-derived partialhydrolysis condensation product are, for example, Methyl Silicate 51 andEthyl Silicate 40 (both being products of Colcoat Co., Ltd.); these canbe used as additives.

For the purpose of inhibiting the surface curability of the curablecomposition from changing during storage, it is preferred that thesilicate be selected from among those in which the silicon atom-boundhydrolyzable groups are the same as the hydrolyzable groups in thereactive silyl group occurring in the organic polymer (A). Thus, whenthe organic polymer (A) contains methoxysilyl groups, a methoxysilylgroup-containing silicate is preferably selected and, when the organicpolymer (A) contains ethoxysilyl groups, an ethoxysilyl group-containingsilicate is preferably selected.

In the curable composition of the invention, there may be incorporated atackifier, if necessary.

The tackifier is not particularly restricted provided that it is one incommon use, irrespective of whether it occurs as a solid or liquid atordinary temperature. For example, there may be mentioned styrene blockcopolymers, hydrogenation products derived therefrom, phenol resins,modified phenol resins (e.g. cashew oil-modified phenol resins, talloil-modified phenol resins), terpene-phenol type resins, xylene-phenoltype resins, cyclopentadiene-phenol type resins, coumarone-indene typeresins, rosin type resins, rosin ester type resins, hydrogenated rosinester type resins, xylene type resins, low-molecular-weight polystyrenetype resins, styrene copolymer resins, petroleum resins (e.g. C5hydrocarbon type resins, C9 hydrocarbon type resins, C5C9 hydrocarboncopolymer resins), hydrogenated petroleum resins, terpene type resins,DCPD resins, and petroleum resins. These may be added singly or aplurality thereof may be added in combination.

The styrene block copolymers and hydrogenation products derivedtherefrom mentioned above are not particularly restricted but include,for example, styrene-butadiene-styrene block copolymers (SBSs),styrene-isoprene-styrene block copolymers (SISs),styrene-ethylenebutylene-styrene block copolymers (SEBSs),styrene-ethylenepropylene-styrene block copolymers (SEPSs) andstyrene-isobutylene-styrene block copolymers (SIBSs).

When a tackifier is added, the addition level thereof is preferably 5 to1,000 parts by weight, more preferably 10 to 100 parts by weight, per100 parts by weight of the organic polymer (A).

In the curable composition of the present invention, there may beincorporated a solvent or diluent, if necessary. The solvent or diluentis not particularly restricted but includes, for example, aliphatichydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, halogenatedhydrocarbons, alcohols, esters, ketones and ethers. These may be addedsingly or a plurality thereof may be added in combination.

When a solvent or diluent is added, the solvent or diluent preferablyhas a boiling point of 150° C. or higher, more preferably 200° C. orhigher, so that the volatile components in the solvent or diluent may beinhibited from dissipating into the air on the occasion of indoor use ofthe curable composition.

In the curable composition of the present invention, there may beincorporated a physical property modifier, if necessary. The physicalproperty modifier functions so as to adjust the tensile characteristicsand hardness of the resulting cured products.

The physical property modifier is not particularly restricted butincludes, for example, alkylalkoxysilanes such asmethyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilaneand n-propyltrimethoxysilane; alkylisopropenoxysilanes such asdimethyldiisopropenoxysilane, methyltriisopropenoxysilane andγ-glycidoxypropylmethyldiisopropenoxysilane; functional group-containingalkoxysilanes such as γ-glycidoxypropylmethyldimethoxysilane,γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane,vinyldimethylmethoxysilane, γ-aminopropyltrimethoxysilane,N-(β-aminoethyl)aminopropylmethyldimethoxysilane,γ-mercaptopropyltrimethoxysilane andγ-mercaptopropylmethyldimethoxysilane; silicone varnishes; andpolysiloxanes. These may be added singly or a plurality thereof may beadded in admixture.

Among such physical property modifiers, those which form, uponhydrolysis, a compound containing a monovalent silanol group in themolecule are preferred since they are effective in reducing the modulusof the resulting cured products without worsening the surface stickinessthereof; among them, those which form, upon hydrolysis, trimethylsilanolare more preferred.

The compounds which form, upon hydrolysis, a compound containingmonovalent silanol group in the molecular are not particularlyrestricted but include: those compounds disclosed in Japanese KokaiPublication H05-117521; compounds derived from an alkyl alcohol, such ashexanol, octanol and decanol, and capable of forming, upon hydrolysis,such an organosilicon compound represented by R₃SiOH astrimethylsilanol; and those compounds disclosed in Japanese KokaiPublication H11-241029 which are compounds derived from a polyhydricalcohol containing 3 or more hydroxyl groups in each molecule, forexample trimethylolpropane, glycerol, pentaerythritol or sorbitol, andcapable of forming, upon hydrolysis, such an organosilicon compoundrepresented by R₃SiOH as trimethylsilanol.

Further, mention may be made of those compounds disclosed in JapaneseKokai Publication H07-258534 which are derived from an oxypropylenepolymer and capable of forming, upon hydrolysis, such an organosiliconcompound represented by R₃SiOH as trimethylsilanol and, further, thosecompounds disclosed in Japanese Kokai Publication H06-279693 whichcontain a crosslinkable hydrolyzable silyl group and a silyl groupcapable of forming, upon hydrolysis, a monovalent silanolgroup-containing compound.

When a physical property modifier is added, the addition level thereofis preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 partsby weight, per 100 parts by weight of the organic polymer (A).

In the curable composition of the present invention, there may beincorporated a thixotropic agent (anti-sagging agent), if necessary. Theterm “thixotropic agent” refers to an agent functioning to prevent thecurable composition from sagging and improve the workability thereof.

The thixotropic agent is not particularly restricted but includes, forexample, polyamide waxes; hydrogenated castor oil derivatives; and metalsoaps such as calcium stearate, aluminum stearate and barium stearate.Further, mention may be made of those rubber powders having a particlediameter of 10 to 500 μm which are disclosed in Japanese KokaiPublication H11-349916, and those organic fibers disclosed in JapaneseKokai Publication 2003-155389. These thixotropic agents (antisaggingagents) may be added singly or a plurality of species may be added incombination.

When a thixotropic agent is added, the addition level thereof ispreferably 0.1 to 20 parts by weight per 100 parts by weight of theorganic polymer (A).

In the curable composition of the present invention, there may beincorporated, for example, a compound containing an epoxy group in eachmolecular, if necessary. By adding an epoxy group-containing compound,it becomes possible to enhance the restorability of the cured productsobtained.

The epoxy group-containing compound is not particularly restricted butincludes, for example, epoxidized unsaturated fats and oils; epoxidizedunsaturated fatty acid esters; alicyclic epoxy compounds;epichlorohydrin derivatives and like compounds; and mixtures thereof.More specifically, there may be mentioned epoxidized soybean oil,epoxidized linseed oil,bis(2-ethylhexyl)-4,5-epoxycyclohexane-1,2-dicarboxylate (E-PS),epoxyoctyl stearate, epoxybutyl stearate and the like. Among these, E-PSis preferred.

When an epoxy compound is added, the addition level thereof ispreferably 0.5 to 50 parts by weight per 100 parts by weight of theorganic polymer (A).

In the curable composition of the present invention, there may be addeda photocurable substance, if necessary. The photocurable substance is asubstance capable of undergoing, under the action of light, chemicalchanges in molecular structure in a short period of time which lead tochanges in physical properties such as curing. The addition of aphotocurable substance to the curable composition results in theformation of a photocurable substance-based layer on the surface of thecured products obtained and thus in improvements in the stickiness andweather resistance of the cured products.

The photocurable substance is not particularly restricted but includesthose known in the art, such as organic monomers, oligomers, resins, andcompositions containing any of them; for example, there may be mentionedunsaturated acrylic compounds, vinyl cinnamate polymers and azidizedresins.

As the unsaturated acrylic compounds, there may be mentioned monomers,oligomers, or mixtures thereof, containing one or a plurality of acrylicor methacrylic unsaturated groups in each molecule, and, specifically,propylene (or butylene or ethylene) glycol di(meth)acrylate, neopentylglycol di(meth)acrylate and like monomers or oligoesters having amolecular weight not exceeding 10,000. More specifically, there may bementioned, for example, such special acrylates as (bifunctional) AronixM-210, Aronix M-215, Aronix M-220, Aronix M-233, Aronix M-240 and AronixM-245; (trifunctional) Aronix M-305, Aronix M-309, Aronix M-310, AronixM-315, Aronix M-320 and Aronix M-325, and (polyfunctional) Aronix M-400(all Aronix products being available from Toagosei Co., Ltd.). Amongthese, acrylic functional group-containing compounds are preferred, andcompounds containing, on an average, 3 or more acrylic functional groupsin each molecule are more preferred.

The vinyl cinnamate polymers are photosensitive resins having cinnamoylgroups as photosensitive groups, which are compounds resulting fromesterification of polyvinyl alcohol with cinnamic acid, and many otherderivatives of vinyl cinnamate polymers.

The azidized resins are known as photosensitive resins in which azidegroups are photosensitive groups and include rubber photosensitivesolutions generally containing a diazide compound added as aphotosensitizer and, further, those detailed examples are described in“Kankosei Jushi (Photosensitive Resins)” (published Mar. 1, 1972 byInsatsu Gakkai Shuppanbu Ltd., p. 93 ff., p. 106 ff., and p. 117 ff.).These may be used either singly or in admixture, if necessary togetherwith a sensitizer.

In some cases, the addition of a sensitizer such as a ketone and nitrocompound or a promoter such as an amine enhances the effect.

When a photocurable substance is added, the addition level thereof ispreferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts byweight, per 100 parts by weight of the organic polymer (A). At levels of0.1 part by weight or below, the effect of enhancing the weatherresistance of the cured products obtained is very little and, at levelsof 20 parts by weight or above, the cured products obtained are toohard, tending to undergo cracking or the like.

In the curable composition of the present invention, there may beincorporated an oxygen-curable substance, if necessary. Theoxygen-curable substance can be cured upon reaction with oxygen in theair, and the addition of an oxygen-curable substance makes it possibleto reduce the stickiness of the cured product surface and to preventdirt and dust from adhering to the surface through the formation of acured layer in the vicinity of the cured product surface obtained.

The oxygen-curable substance is not particularly restricted but may beany of the compounds containing an unsaturated compound capable ofreacting with oxygen in the air; thus, for example, there may bementioned drying oils such as tung oil and linseed oil, and variousalkyd resins obtained by modifying such compounds; drying oil-modifiedacrylic polymers, epoxy type resins and silicone type resins; liquidpolymers obtained by polymerizing or copolymerizing such a dienecompound(s) as butadiene, chloroprene, isoprene and 1,3-pentadiene, forexample 1,2-polybutadiene, 1,4-polybutadiene and C₅-C₈ diene polymers;liquid copolymers obtained by copolymerizing such a diene compound witha vinyl compound, such as acrylonitrile and styrene, copolymerizablewith the diene compound, in a manner such that the diene compound serveas the main component, for example NBR and SBR; and, further, variousmodifications thereof (maleinated modifications, boiled oilmodifications, etc.).

Among those mentioned above, tung oil and liquid diene type polymers arepreferred. The oxygen-curable substance to be added may comprise asingle species or a combination of a plurality of species.

When a catalyst and/or metal dryer which are capable of promoting thecuring reaction are added in admixture with the oxygen-curablesubstance, the effect may be enhanced.

The catalyst and metal dryer for promoting the curing reaction are notparticularly restricted but include, for example, metal salts such ascobalt naphthenate, lead naphthenate, zirconium naphthenate, cobaltoctylate and zirconium octylate, and amine compounds.

When an oxygen-curable substance is added, the addition level thereof ispreferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts byweight, per 100 parts by weight of the organic polymer (A). At additionlevels below 0.1 part by weight, the effect of improving the stainresistance of the cured products obtained tends to become insufficientand, at levels exceeding 20 parts by weight, the tensile characteristicsand the like of the cured products obtained tend to become impaired.

Further, the oxygen-curable substance is preferably added in admixturewith a photocurable substance, as disclosed in Japanese KokaiPublication H03-160053.

In the curable composition of the present invention, there may beincorporated an antioxidant, if necessary. By adding an antioxidant, itbecomes possible to enhance the thermal stability of the cured productsobtained.

The antioxidant is not particularly restricted but includes hinderedphenol type, monophenol type, bisphenol type and polyphenol typeantioxidants. Among these, hindered phenol type antioxidants arepreferred. Also preferred are hindered amine type light stabilizers suchas Tinuvin 622LD and Tinuvin 144; Chimassorb 944 LD and Chimassorb 119FL(all four being products of Chiba Specialty Chemicals); ADK STAB LA-57,ADK STAB LA-62, ADK STAB LA-67, ADK STAB LA-63 and ADK STAB LA-68 (allfive being products of Adeka Corporation); and Sanol LS-770, SanolLS-765, Sanol LS-292, Sanol LS-2626, Sanol LS-1114 and Sanol LS-744 (allsix being product of Sankyo Lifetech Co., Ltd.). Specific examples ofthe antioxidants are disclosed also in Japanese Kokai PublicationsH04-283259 and H09-194731.

When an antioxidant is added, the addition level thereof is preferably0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, per100 parts by weight of the organic polymer (A).

In the curable composition of the present invention, there may beincorporated a light stabilizer, if necessary. By adding a lightstabilizer, the cured products obtained can be prevented from undergoingphotooxidative degradation.

The light stabilizer is not particularly restricted but includesbenzotriazole type, hindered amine type and benzoate type compounds.Among these, hindered amine type light stabilizers are preferred.

When a light stabilizer is added, the addition level thereof ispreferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts byweight, per 100 parts by weight of the organic polymer (A). A specificexample of the light stabilizer is disclosed in Japanese KokaiPublication H09-194731 as well.

When such a photocurable substance as an unsaturated acrylic compound isadded to the curable composition of the present invention, a tertiaryamine group-containing hindered amine type light stabilizer ispreferably added as disclosed in Japanese Kokai Publication H05-70531since, then, the storage stability of the curable composition isimproved.

The tertiary amine group-containing hindered amine type light stabilizeris not particularly restricted but includes Tinuvin 622LD, Tinuvin 144and Chimassorb 119FL (all three being products of Ciba SpecialtyChemicals Inc.); ADK STAB LA-57, LA-62, LA-67 and LA-63 (all four beingproducts of Adeka Corporation); and Sanol LS-765, LS-292, LS-2626,LS-1114 and LS-744 (all five being products of Sankyo Lifetech Co.,Ltd.)

To the curable composition of the present invention may be added anultraviolet absorber, if necessary. When an ultraviolet absorber isadded to the curable composition, the surface weather resistance of thecured products obtained is improved.

The ultraviolet absorber is not particularly restricted but includesbenzophenone type, benzotriazole type, salicylate type, substitutedtolyl type and metal chelate type compounds.

Among these, benzotriazole type ultraviolet absorbers are preferred.

When an ultraviolet absorber is added to the curable composition, theaddition level thereof is preferably 0.1 to 10 parts by weight, morepreferably 0.2 to 5 parts by weight, per 100 parts by weight of theorganic polymer (A).

The antioxidant, light stabilizer and ultraviolet absorber mentionedabove are preferably added in combination to the curable compositionand, for example, a phenol or hindered phenol antioxidant, a hinderedamine type light stabilizer and a benzotriazole type ultravioletabsorber are preferably added in admixture with the curable composition.

To the curable composition of the present invention may be added a flameretardant, if necessary. The flame retardant is not particularlyrestricted; thus, for example, phosphorus type flame retardants such asammonium polyphosphate and tricresyl phosphate; aluminum hydroxide,magnesium hydroxide, and flame retardants such as thermally expandablegraphite may be added to the curable composition. The flame retardant tobe added thereto may comprise a single species or a combination of aplurality of species.

When a flame retardant is added to the curable composition, the additionlevel thereof is preferably 5 to 200 parts by weight, more preferably 10to 100 parts by weight, per 100 parts by weight of the organic polymer.

To the curable composition of the present invention may be added, ifnecessary, various additives other than those mentioned above for thepurpose of adjusting various physical properties of the curablecomposition or of the cured products to be obtained. As such additives,there may be mentioned, for example, curability modifiers, radicalinhibitors, metal deactivators, antiozonants, phosphorus type peroxidedecomposers, lubricants, pigments, blowing agents, antitermites andantifungal agents. Specific examples of these are disclosed inpublications such as Japanese Kokoku Publications H04-69659 andH07-108928, and Japanese Kokai Publications S63-254149, S64-22904 and2001-72854. These additives may be added singly to the curablecomposition or a plurality thereof may be added in combination to thecurable composition.

In cases where the curable composition is of the one-pack type, thecomposition contains all components as mixed up in advance and, thus,curing may proceed during storage if moisture is present in formulationcomponents. Therefore, those formulation components which containmoisture are preferably dehydrated and dried prior to addition ordehydrated during compounding and kneading by reducing the pressure, forinstance.

When the curable composition is of the two-pack type, it is notnecessary to incorporate the curing catalyst in the main componenthaving a reactive silyl group-containing organic polymer and, therefore,even if some moisture is contained in the formulation components, therisk of the progress of curing (gelation) is low; in cases wherelong-term storage stability is required, however, it is preferred thatthe formulation components be dehydrated or dried.

As for the method of dehydrating or drying, the method comprising dryingby heating or the method comprising dehydrating under reduced pressureare preferred in cases where the formulation components are solids suchas powders and, in cases where they are liquids, the vacuum dehydrationmethod and the dehydration method using a synthetic zeolite, activatedalumina, silica gel, quick lime, magnesium oxide or the like arepreferred and, further, the dehydration method comprising adding analkoxysilane compound such as n-propyltrimethoxysilane,vinyltrimethoxysilane, vinylmethyldimethoxysilane, methyl silicate,ethyl silicate, γ-mercpatopropylmethyldimethoxysilane,γ-mercaptopropylmethyldiethoxysilane andγ-glycidoxypropyltrimethoxysilane; an oxazolidine compound such as3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine; and an isocyanatecompound to the curable composition and allowing the same to react withwater contained in the formulation components is also preferred. In thisway, the storage stability of the curable composition is improved by theaddition of such an alkoxysilane compound, oxazolidine compound andisocyanate compound.

In using vinyltrimethoxysilane or a like alkoxysilane compound capableof reacting with water for the purpose of drying, the addition levelthereof is preferably 0.1 to 20 parts by weight, more preferably 0.5 to10 parts by weight, per 100 parts by weight of the organic polymer (A).

The method of preparing the curable composition of the present inventionis not particularly restricted but there may be employed, for example,such a method known in the art as a method comprising combining theformulation components mentioned above and kneading the resultingmixture at ordinary temperature or with heating using a mixer, roller,kneader, or the like, or a method comprising dissolving the formulationcomponents using small portions of an appropriate solvent and thenmixing up the solutions.

When exposed to the air, the curable composition of the presentinvention forms a three-dimensional network structure under the actionof atmospheric moisture and thus is cured to give a solid having rubberelasticity.

The curable composition of the present invention can be suitably used insuch fields of application as pressure-sensitive adhesives; sealants forbuildings, ships, automobiles, roads, etc.; adhesives; impressionmaterials; vibration-proof materials; damping materials; soundproofmaterials; expanded/foamed materials; coating compositions; spraycoatings, etc. Among such fields of application, the use as sealants oradhesives is more preferred since the cured products obtained areexcellent in flexibility and adhesiveness.

The curable composition of the present invention can also be used insuch fields of application as back cover sealants for a solar cell andlike electric and electronic part materials; insulating cover materialsfor electric wires and cables and other electric insulating materials;elastic adhesives; contact adhesives; spray sealants; crack repairmaterials; tiling adhesives; powder coating compositions; castingmaterials; rubber materials for medical use; pressure-sensitiveadhesives for medical use; sealants for medical devices; food packagingmaterials; joint sealants for siding boards and other exteriormaterials; coating materials; primers; electromagnetic wave shieldingconductive materials, thermally conductive materials; hot meltmaterials; potting agents for electrics and electronics; films; gaskets;various molding materials; rustproof and waterproof sealants for wiredglass and laminated-glass edges (cut end faces); liquid sealants for usein automotive parts, electrical machinery parts, various machineryparts, etc.

Further, the curable composition can also be used as various types ofhermetically sealants and adhesives since it, either alone or with theaid of a primer, can adhere to a wide range of substrates such as glass,ceramics, wood, metals and resin moldings.

The curable composition of the present invention can also be used in theform of interior panel adhesives, exterior panel adhesives, tilingadhesives, stone pitching adhesives, ceiling finishing adhesives, floorfinishing adhesives, wall finishing adhesives, vehicle panel adhesives,electric, electronic and precision apparatus assembling adhesives,direct glazing sealants, double glazing sealants, sealants for SSGsystems, or building working joint sealants.

BEST MODE FOR CARRYING OUT THE INVENTION

The following examples and comparative examples illustrate the presentinvention more specifically. These are, however, by no means limitativeof the scope of the present invention.

Synthesis Example 1

Propylene oxide was polymerized using polyoxypropylene diol with amolecular weight of about 2,000 as an initiator and a zinchexacyanocobaltate glyme complex catalyst to give polypropylene oxidehaving a number average molecular weight of about 25,500(polystyrene-equivalent molecular weight measured by using a TOSOH modelHLC-8120 GPC solvent delivery system, a TOSOH model TSK-GEL H typecolumn, with THF as a solvent). Thereto was then added a methanolsolution of NaOMe in an amount of 1.2 equivalents relative to thehydroxyl groups of that hydroxyl-terminated polypropylene oxide, themethanol was distilled off and, further, allyl chloride was added to theresidue for conversion of each terminal hydroxyl group to an allylgroup. The unreacted allyl chloride was removed by volatilization underreduced pressure. To 100 parts by weight of the crude allyl-terminatedpolypropylene oxide obtained were added 300 parts by weight of n-hexaneand 300 parts by weight of water and, after mixing with stirring, thewater was removed by centrifugation. The hexane solution obtained wasfurther mixed with 300 parts by weight of water with stirring, and afterthe water was removed again by centrifugation, the hexane was removed byvolatilization under reduced pressure. In the above manner,allyl-terminated bifunctional polypropylene oxide with a number averagemolecular weight of about 25,500 was obtained (this product ishereinafter referred to as a “polymer P”).

The polymer (P) (100 parts by weight) was reacted with 0.80 part byweight of methyldimethoxysilane at 90° C. for 5 hours in the presence of150 ppm of an isopropanol solution of a platinum-vinylsiloxane complex(platinum content: 3% by weight) as a catalyst to give amethyldimethoxysilyl group-terminated polyoxypropylene type polymer (A).

As a result of ¹H-NMR measurement (made in CDCl₃ solvent using a NipponDenshi (JEOL Ltd.) model JNM-LA400), the average number of terminalmethyldimethoxysilyl groups per molecule was found to be about 1.3.

Synthesis Example 2

The polymer (P) (100 parts by weight) obtained in Synthesis Example 1was reacted with 0.95 part by weight of trimethoxysilane at 90° C. for 5hours in the presence of 150 ppm of an isopropanol solution of aplatinum-vinylsiloxane complex (platinum content: 3% by weight) as acatalyst to give a trimethoxysilyl group-terminated polyoxypropylenetype polymer (T). As a result of ¹H-NMR measurement, the number ofterminal trimethoxysilyl groups was found to be about 1.3 per moleculeon an average.

Example 1

Surface-treated colloidal calcium carbonate (120 parts by weight;product of Shiraishi Kogyo Kaisha Ltd., trade name: Hakuenka CCR), 20parts by weight of titanium oxide (product of Ishihara Sangyo KaishaLtd., trade name: Tipaque R-820), 55 parts by weight of a plasticizer(product of Kyowa Hakko Kogyo Co., Ltd., trade name: DIDP), 2 parts byweight of a thixotropic agent (product of Kusumoto Chemicals Ltd., tradename: Disparlon #6500), 1 part by weight of an ultraviolet absorber(product of Ciba Specialty Chemicals Inc., trade name: Tinuvin 327) and1 part by weight of a light stabilizer (product of Sankyo Co., Ltd.,trade name: Sanol LS770) were weighed and admixed with 100 parts byweight of the methyldimethoxysilyl group-terminated polyoxypropylenetype polymer (A) obtained in Synthesis Example 1 and, after thoroughkneading, the mixture was passed through a three-roll paint mill fordispersion.

Thereafter, the mixture was dehydrated at 120° C. for 2 hours underreduced pressure and, after cooling to a temperature not higher than 50°C., 5 parts by weight of γ-(2-aminoethyl)aminopropyltrimethoxysilane(product of Dow Corning Toray Co., Ltd., trade name: A-1120) as the (D)component adhesiveness-imparting agent, 3 parts by weight ofγ-glycidoxypropyltrimethoxysilane (product of Dow Corning Toray Co.,Ltd., trade name: A-187), 10 parts by weight of 1-(o-tolyl)biguanide(product of Tokyo Chemical Industry Co., Ltd., abbreviated as OTBG) asthe (B-1) component silanol condensation catalyst and 9 parts by weightof neodecanoic acid (product of Japan Epoxy Resins Co., Ltd., tradename: Versatic 10) as the (C) component carboxylic acid were added andkneaded. After kneading under substantially water-free conditions, theresulting mixture was hermetically packed in a moisture-proof container.A one-pack type curable composition was thus obtained.

Since the (B-1) component OTBG has a molecular weight of 191.2 and the(D) component Versatic 10 has a molecular weight of 172.3, the ratiobetween the number of moles (b) of all nitrogen atoms in the (B-1)component and the number of moles (c) of all carboxyl groups in the (C)component, namely the ratio (b)/(c), was 5.

Example 2

A curable composition was obtained in the same manner as in Example 1except that Versatic 10 was used in an amount of 4.5 parts by weight.The ratio between the number of moles (b) of all nitrogen atoms in the(B-1) component and the number of moles (c) of all carboxyl groups inthe (C) component, namely the ratio (b)/(c), was 10.

Example 3

A curable composition was obtained in the same manner as in Example 1except that Versatic 10 was used in an amount of 2.3 parts by weight.The ratio between the number of moles (b) of all nitrogen atoms in the(B-1) component and the number of moles (c) of all carboxyl groups inthe (C) component, namely the ratio (b)/(c), was 20.

Comparative Example 1

A curable composition was obtained in the same manner as in Example 1except that Versatic 10 used in Example 1 was not used.

Comparative Example 2

A curable composition was obtained in the same manner as in ComparativeExample 1 except that the organic polymer (T) was used in lieu of theorganic polymer (A) used in Comparative Example 1 and OTBG was used inan amount of 4 parts by weight.

(Surface Curability)

Under constant temperature (23° C.) and constant humidity (50%)conditions, each of the above curable compositions was spread to athickness of about 3 mm, and the surface of the curable composition wastouched gently with a microspatula from time to time and the timerequired for the composition to become no more sticking to themicrospatula was determined. The results thus obtained are shown inTable 1.

(Depth Curability)

Under constant temperature (23° C.) and constant humidity (50%)conditions, a polyethylene tube with an inside diameter of 18 mm and alength of 50 mm was filled with each of the above curable compositionsand, after 7 days of curing, the cured portion was taken out and thelength of the cured portion was measured. The results thus obtained areshown in Table 1.

(Adhesiveness)

Each of the above curable compositions, in the form of a rectanglehaving an approximate size of 3.0 cm in length, 1.5 cm in width and 1.0cm in thickness, was brought into close contact with an adherendsubstrate (electrolytically colored aluminum, stainless steel and vinylchloride resin) and cured under constant temperature (23° C.) andconstant humidity (50%) conditions for 7 days; then, the adhesivenesswas evaluated by 90-degree hand peel test. The adhesiveness evaluationwas made in terms of fracture mode. In the case of 80 to 100% cohesivefailure, the adhesiveness was evaluated as A; in the case of 40% tobelow 80% cohesive failure, as B; and in the case of 0% to below 40%cohesive failure, as C. The results thus obtained are shown in Table 1.

TABLE 1 Examples Comparative Examples 1 2 3 1 2 Composi- Organic polymer(A) 100 100 100 100 tion Organic polymer (T) 100 (parts Filler HakuenkaCCR Shiraishi Kogyo 120 120 120 120 120 by wt.) Titanium oxide TipaqueR-820 Ishihara Sangyo 20 20 20 20 20 Plasticizer DIDP Kyowa Hakko 55 5555 55 55 Thixotropic Disparlon #6500 Kusumoto 2 2 2 2 2 agent ChemicalsUltraviolet Tinuvin 327 Ciba Specialty 1 1 1 1 1 absorber ChemicalsLight stabilizer Sanol LS770 Sankyo 1 1 1 1 1 Adhesiveness- A-1120 DowCorning Toray 5 5 5 5 5 imparting agent A-187 Dow Corning Toray 3 3 3 33 Amidine compound OTBG Tokyo Chemical 10 10 10 10 4 (B) IndustryCarboxylic acid Versatic 10 Japan Epoxy 9 4.5 2.3 (C) Resins (b)/(c) 510 20 — — Results Surface curability (time required for layer formation)5.5 hours 5.5 hours 8 hours 15 hours 48 minutes Depth curability 2.5 mm2.3 mm 2.1 mm 1.9 mm Tensile 100% tensile modulus 0.48 MPa 0.45 MPa 0.47MPa 0.43 MPa 0.74 MPa characteristics Breaking strength 1.45 MPa 1.50MPa 1.62 MPa 1.46 MPa 1.35 MPa Breaking elongation 490% 570% 630% 640%240% Adhesiveness (90-degree hand peel) Electrolytically B A A B coloredalminum Stainless steel A A A B Vinyl chloride A A A C resin

When, as shown in Examples 1 to 3, OTBG was used as the (B-1) component,Versatic 10 was further added as the (C) component and, further, theratio between the number of moles (b) of all nitrogen atoms in the (B-1)component and the number of moles (c) of all carboxyl groups in the (C)component, namely the ratio (b)/(c), was higher than 2, the surfacecurability, depth curability and adhesiveness were good. On the otherhand, in Comparative Example 1 in which the addition of the (C)component was omitted, the surface curability, depth curability andadhesiveness were all inferior. In Comparative Example 2 in which theaddition of the (C) component was omitted and the trimethoxysilylgroup-terminated polyoxypropylene polymer (T) was used, the modulus washigh and the elongation was inferior.

Examples 4 to 6 and Comparative Examples 3 and 4

To 100 parts by weight of the methyldimethoxysilyl group-terminatedpolyoxypropylene type polymer (A) obtained in Synthesis Example 1 wereadded 120 parts by weight of surface-treated colloidal calcium carbonate(Hakuenka CCR), 20 parts by weight of titanium oxide (Tipaque R-820), 55parts by weight of a plasticizer (DIDP), 2 parts by weight of athixotropic agent (Disparlon #6500), 1 part by weight of an ultravioletabsorber (Tinuvin 327) and 1 part by weight of a light stabilizer (SanolLS770). After thorough kneading, the mixture was passed through athree-roll paint mill for dispersion and dehydrated at 120° C. for 2hours under reduced pressure; thus, a main composition was prepared.Under constant temperature (23° C.) and constant humidity (50%)conditions, 2 parts by weight of a dehydrating agent (A-171), 3 parts byweight of γ-(2-aminoethyl)aminopropyltrimethoxysilane (product of DowCorning Toray Co., Ltd., trade name: A-1120) as the (D) componentadhesiveness-imparting agent, 1-(o-tolyl) biguanide (OTBG) as the (B-1)component silanol condensation catalyst and neodecanoic acid (Versatic10) as the (C) component carboxylic acid were added to the maincomposition according to each formulation given in Table 2. Eachcompound, in the form of a rectangle having an approximate size of 3.0cm in length, 1.5 cm in width and 1.0 cm in thickness, was brought intoclose contact with an adherend substrate (electrolytically coloredaluminum, stainless steel and vinyl chloride resin) and cured underconstant temperature (23° C.) and constant humidity (50%) conditions for7 days; then, the adhesiveness was evaluated by 90-degree hand peeltest. The results thus obtained are shown in Table 2. The adhesivenessevaluation was made in terms of fracture mode. In the case of 80 to 100%cohesive failure, the adhesiveness was evaluated as A; in the case of40% to below 80% cohesive failure, as B; and in the case of 0% to below40% cohesive failure, as C.

The value of the ratio between the number of moles (b) of all nitrogenatoms in the (B-1) component and the number of moles (c) of all carboxylgroups in the (C) component, namely the ratio (b)/(c), is shown for eachcompound in Table 2.

TABLE 2 Examples Comparative Examples 4 5 6 3 4 Composition Main Organicpolymer (A) 100 100 100 100 100 (parts by wt.) composition FillerHakuenka CCR Shiraishi Kogyo 120 120 120 120 120 Titanium Oxide TipaqueR-820 Ishihara Sangyo 20 20 20 20 20 Plasticizer DIDP Kyowa Hakko 55 5555 55 55 Thixotropic agent Disparlon #6500 Kusumoto 2 2 2 2 2 ChemicalsUltraviolet absorber Tinuvin 327 Ciba Specialty 1 1 1 1 1 ChemicalsLight stabilizer Sanol LS770 Sankyo 1 1 1 1 1 Dehydrating agent A-171Dow Corning 2 2 2 2 2 Toray Adhesiveness-imparting agent A-1120 DowCorning 3 3 3 3 3 Toray Amidine compound (B) OTBG Tokyo Chemical 8.3 8.38.3 8.3 2.1 Industry Carboxylic acid (C) Versatic 10 Japan Epoxy 7.5 3.71.9 22.5 7.5 Resins (b)/(c) 5 10 20 1.7 1.3 Results Adhesiveness(90-degree hand peel) Electrolytically A A B C C colored alminumStainless steel A A A C C Vinyl chloride A A A C C resin

When, as shown in Examples 4 to 6, OTBG was used as the (B-1) component,further Versatic 10 was added as the (C) component and the ratio betweenthe number of moles (b) of all nitrogen atoms in the (B-1) component andthe number of moles (c) of all carboxyl groups in the (C) component,namely the ratio (b)/(c), was higher than 2, the adhesiveness was good.

On the other hand, when the ratio (b)/(c) was not higher than 2, theadhesiveness was inferior, as shown in Comparative Example 3 or 4.

1. A non-organotin curable composition which comprises: (A) an organicpolymer containing a silyl group capable of crosslinking under siloxanebond formation, said silyl group being a group represented by thegeneral formula (1):—SiR¹X₂  (1) (wherein R¹ represents a group selected from among alkylgroups containing 1 to 20 carbon atoms, aryl groups containing 6 to 20carbon atoms, aralkyl groups containing 7 to 20 carbon atoms andtriorganosiloxy groups represented by (R′)₃SiO— in which R′ is ahydrocarbon group containing 1 to 20 carbon atoms, the three R′ groupsmay be the same or different, and X represents a hydroxyl group or ahydrolyzable group and the two X groups may be the same or different);(B) an amidine compound (B-1) as a silanol condensation catalyst; and(C) a carboxylic acid, wherein the ratio between the number of moles (b)of all nitrogen atoms in the (B-1) component of the composition and thenumber of moles (c) of all carboxyl groups in the (C) component of thecomposition, namely the ratio (b)/(c), is higher than
 2. 2. The curablecomposition according to claim 1, wherein a main chain skeleton of the(A) component organic polymer contains at least one atom selected fromamong a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atomand a sulfur atom.
 3. The curable composition according to claim 1,wherein the (A) component organic polymer comprises at least one speciesselected from the group consisting of polyoxyalkylene polymers,saturated hydrocarbon polymers and (meth)acrylate ester polymers.
 4. Thecurable composition according to claim 3, wherein the polyoxyalkylenepolymer is a polyoxypropylene polymer.
 5. The curable compositionaccording to claim 1, which contains the (B-1) component in an amount of0.001 to 20 parts by weight per 100 parts by weight of the component(A).
 6. A sealant which comprises the curable composition according toclaim
 1. 7. An adhesive which comprises the curable compositionaccording to claim 1.